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1.
Indian J Exp Biol ; 49(5): 375-86, 2011 May.
Article in English | MEDLINE | ID: mdl-21615063

ABSTRACT

Saturated hydrocarbons (SHC) of five cruciferous host plants viz., cabbage, cauliflower, broccoli, knol khol and Brussels sprout and the larvae of diamondback moth (DBM), Plutella xylostella reared on these host plants were identified through gas-chromatography. The hydrocarbon profile of host plants and larval body extract of DBM reared on respective host plants revealed a wide variation in quantity as well as quality. Long chain hydrocarbons C26-C30 were detected in all the extracts. In electroantennogram (EAG) studies, SHCs at 10(-3) g dose elicited differential EAG response in the antennal receptors of gravid Cotesia plutellae females. Tricosane (C23) and hexacosane (C26) elicited 10-fold increased EAG response compared to control stimulus. Long chain hydrocarbons C27, C28 and C29 elicited, 6-7 fold increased responses. The sensitivity of antenna was 4-5 folds for C25, C14, C24, C15 and C30, while the short chain hydrocarbons elicited 2-3 fold increased EAG responses. Dual choice flight orientation experiments in a wind tunnel revealed that the gravid C. plutellae females preferred the odour of C16, C26, C29, C15, C21, C23, C30, C27, C24 and C22 as 60-70% females oriented and landed on SHC treated substrate compared to control odour, while the odour of eicosane (C20), pentacosane (C25) and octacosane (C28) were not preferred by the females.


Subject(s)
Hydrocarbons/analysis , Hymenoptera/pathogenicity , Moths/parasitology , Plants/chemistry , Plants/parasitology , Animals , Behavior, Animal , Chromatography, Gas , Female , Flight, Animal , Host-Parasite Interactions , Larva/chemistry , Larva/parasitology , Moths/chemistry , Odorants/analysis
3.
J Virol ; 75(22): 10979-90, 2001 Nov.
Article in English | MEDLINE | ID: mdl-11602738

ABSTRACT

We have previously shown that the RNA polymerase 3D(pol) of human rhinovirus 2 (HRV2) catalyzes the covalent linkage of UMP to the terminal protein (VPg) using poly(A) as a template (K. Gerber, E. Wimmer, and A. V. Paul, J. Virol. 75:10969-10978, 2001). The products of this in vitro reaction are VPgpU, VPgpUpU, and VPg-poly(U), the 5' end of minus-strand RNA. In the present study we used an assay system developed for poliovirus 3D(pol) (A. V. Paul, E. Rieder, D. W. Kim, J. H. van Boom, and E. Wimmer, J. Virol. 74: 10359-10370, 2000) to search for a viral sequence or structure in HRV2 RNA that would provide specificity to this reaction. We now show that a small hairpin in HRV2 RNA [cre(2A)], located in the coding sequence of 2A(pro), serves as the primary template for HRV2 3D(pol) in the uridylylation of HRV2 VPg, yielding VPgpU and VPgpUpU. The in vitro reaction is strongly stimulated by the addition of purified HRV2 3CD(pro). Our analyses suggest that HRV2 3D(pol) uses a "slide-back" mechanism during synthesis of the VPg-linked precursors. The corresponding cis- replicating RNA elements in the 2C(ATPase) coding region of poliovirus type 1 Mahoney (I. Goodfellow, Y. Chaudhry, A. Richardson, J. Meredith, J. W. Almond, W. Barclay, and D. J. Evans, J. Virol. 74:4590-4600, 2000) and VP1 of HRV14 (K. L. McKnight and S. M. Lemon, RNA 4:1569-1584, 1998) can be functionally exchanged in the assay with cre(2A) of HRV2. Mutations of either the first or the second A in the conserved A(1)A(2)A(3)CA sequence in the loop of HRV2 cre(2A) abolished both viral growth and the RNA's ability to serve as a template in the in vitro VPg uridylylation reaction.


Subject(s)
Genes, Viral , RNA, Viral/biosynthesis , Rhinovirus/genetics , Amino Acid Sequence , Base Sequence , Molecular Sequence Data , Oligoribonucleotides/chemistry , Oligoribonucleotides/metabolism , RNA, Viral/chemistry , RNA-Dependent RNA Polymerase/metabolism , Uridine Triphosphate/metabolism , Viral Proteins/chemistry , Viral Proteins/metabolism
4.
J Virol ; 75(22): 10969-78, 2001 Nov.
Article in English | MEDLINE | ID: mdl-11602737

ABSTRACT

The replication of human rhinovirus 2 (HRV2), a positive-stranded RNA virus belonging to the Picornaviridae, requires a virus-encoded RNA polymerase. We have expressed in Escherichia coli and purified both a glutathione S-transferase fusion polypeptide and an untagged form of the HRV2 RNA polymerase 3D(pol). Using in vitro assay systems previously described for poliovirus RNA polymerase 3D(pol) (J. B. Flanegan and D. Baltimore, Proc. Natl. Acad. Sci. USA 74:3677-3680, 1977; A. V. Paul, J. H. van Boom, D. Filippov, and E. Wimmer, Nature 393:280-284, 1998), we have analyzed the biochemical properties of the two different enzyme preparations. HRV2 3D(pol) is both template and primer dependent, and it catalyzes two types of synthetic reactions in the presence of UTP, Mn(2+), and a poly(A) template. The first consists of an elongation reaction of an oligo(dT)(15) primer into poly(U). The second is a protein-priming reaction in which the enzyme covalently links UMP to the hydroxyl group of tyrosine in the terminal protein VPg, yielding VPgpU. This precursor is elongated first into VPgpUpU and then into VPg-linked poly(U), which is identical to the 5' end of picornavirus minus strands. The two forms of the enzyme are about equally active both in the oligonucleotide elongation and in the VPg-primed reaction. Various synthetic mutant VPgs were tested as substrates in the VPg uridylylation reaction.


Subject(s)
RNA, Viral/biosynthesis , RNA-Dependent RNA Polymerase/isolation & purification , Rhinovirus/genetics , Amino Acid Sequence , Humans , Molecular Sequence Data , Oligoribonucleotides/chemistry , Oligoribonucleotides/metabolism , Poly U/biosynthesis , RNA-Dependent RNA Polymerase/metabolism , Uridine Triphosphate/metabolism , Viral Proteins/chemistry , Viral Proteins/metabolism
5.
J Virol ; 74(22): 10359-70, 2000 Nov.
Article in English | MEDLINE | ID: mdl-11044080

ABSTRACT

The first step in the replication of the plus-stranded poliovirus RNA is the synthesis of a complementary minus strand. This process is initiated by the covalent attachment of UMP to the terminal protein VPg, yielding VPgpU and VPgpUpU. We have previously shown that these products can be made in vitro in a reaction that requires only synthetic VPg, UTP, poly(A), purified poliovirus RNA polymerase 3D(pol), and Mg(2+) (A. V. Paul, J. H. van Boom, D. Filippov, and E. Wimmer, Nature 393:280-284, 1998). Since such a poly(A)-dependent process cannot confer sufficient specificity to poliovirus RNA replication, we have developed a new assay to search for a viral RNA template in conjunction with viral or cellular factors that could provide this function. We have now discovered a small RNA hairpin in the coding region of protein 2C as the site in PV1(M) RNA that is used as the primary template for the in vitro uridylylation of VPg. This hairpin has recently been described in poliovirus RNA as being an essential structure for the initiation of minus strand RNA synthesis (I. Goodfellow, Y. Chaudhry, A. Richardson, J. Meredith, J. W. Almond, W. Barclay, and D. J. Evans, J. Virol. 74:4590-4600, 2000). The uridylylation reaction either with transcripts of cre(2C) RNA or with full-length PV1(M) RNA as the template is strongly stimulated by the addition of purified viral protein 3CD(pro). Deletion of the cre(2C) RNA sequences from minigenomes eliminates their ability to serve as template in the reaction. A similar signal in the coding region of VP1 in HRV14 RNA (K. L. McKnight and S. M. Lemon, RNA 4:1569-1584, 1998) and the poliovirus cre(2C) can be functionally exchanged in the assay. The mechanism by which the VPgpUpU precursor, made specifically on the cre(2C) template, might be transferred to the site where it serves as primer for poliovirus RNA synthesis, remains to be determined.


Subject(s)
Nucleic Acid Conformation , Poliovirus/metabolism , RNA, Viral/chemistry , RNA, Viral/metabolism , Viral Core Proteins/metabolism , Base Sequence , DNA-Directed RNA Polymerases/metabolism , Genome, Viral , Humans , Molecular Sequence Data , Poliovirus/genetics , Protein Biosynthesis , RNA, Viral/genetics , Templates, Genetic , Transcription, Genetic , Uridine Monophosphate/metabolism , Viral Core Proteins/genetics , Virus Replication
6.
J Virol ; 74(22): 10371-80, 2000 Nov.
Article in English | MEDLINE | ID: mdl-11044081

ABSTRACT

In addition to highly conserved stem-loop structures located in the 5'- and 3'-nontranslated regions, genome replication of picornaviruses requires cis-acting RNA elements located in the coding region (termed cre) (K. L. McKnight and S. M. Lemon, J. Virol. 70:1941-1952, 1996; P. E. Lobert, N. Escriou, J. Ruelle, and T. Michiels, Proc. Natl. Acad. Sci. USA 96:11560-11565, 1999; I. Goodfellow, Y. Chaudhry, A. Richardson, J. Meredith, J. W. Almond, W. Barclay, and D. J. Evans, J. Virol. 74:4590-4600, 2000). cre elements appear to be essential for minus-strand RNA synthesis by an as-yet-unknown mechanism. We have discovered that the cre element of poliovirus (mapping to the 2C coding region of poliovirus type 1; nucleotides 4444 to 4505 in 2C), which is homologous to the cre element of poliovirus type 3, is preferentially used as a template for the in vitro uridylylation of VPg catalyzed by 3D(pol) in a reaction that is greatly stimulated by 3CD(pro) (A. V. Paul, E. Rieder, D. W. Kim, J. H. van Boom, and E. Wimmer, J. Virol. 74:10359-10370, 2000). Here we report a direct correlation between mutations that eliminate, or severely reduce, the in vitro VPg-uridylylation reaction and produce replication phenotypes in vivo. None of the genetic changes significantly influenced translation or polyprotein processing. A substitution mapping to the first A (A4472C) of a conserved AAACA sequence in the loop of PV-cre(2C) eliminated the ability of the cre RNA to serve as template for VPg uridylylation and abolished RNA infectivity. Mutagenesis of the second A (A4473C; AAACA) severely reduced the yield of VPgpUpU and RNA infectivity was restored only after reversion to the wild-type sequence. The effect of substitution of the third A (A4474G; AAACA) was less severe but reduced both VPg uridylylation and virus yield. Disruption of base pairing within the upper stem region of PV-cre(2C) also affected uridylylation of VPg. Virus derived from transcripts containing mutations in the stem was either viable or quasi-infectious.


Subject(s)
Poliovirus/genetics , Poliovirus/physiology , RNA, Viral/chemistry , Viral Core Proteins/metabolism , Viral Proteins/metabolism , Virus Replication/genetics , Base Sequence , HeLa Cells , Humans , Molecular Sequence Data , Mutation , Nucleic Acid Conformation , Phenotype , Plasmids/genetics , Poliovirus/chemistry , RNA, Viral/genetics , RNA, Viral/metabolism , Transfection , Uridine Monophosphate/metabolism , Viral Proteins/genetics
7.
Virology ; 272(1): 72-84, 2000 Jun 20.
Article in English | MEDLINE | ID: mdl-10873750

ABSTRACT

Determinants of temperature sensitivity and/or attenuation in Sabin type 1 poliovirus reside in the 5' NTR and coding sequences of the capsid proteins and viral RNA polymerase, 3D(pol). Previous studies have implicated at least two mutations in 3D(pol) of Sabin 1 vaccine strain [PV1(S)], including a Y73H change, as contributing to these phenotypes. We have used an in vitro assay to test the first step in RNA synthesis, the uridylylation of the terminal protein VPg with 3D(pol) isolated from PV1(S). Wt and two mutant 3D(pol) proteins (Y73H, D53N/Y73H) were expressed in Escherichia coli and were purified, and their activities were measured in the synthesis of VPgpU(pU) and of VPg-linked poly(U) at 30 and 39.5 degrees C. Our results show that at 39.5 degrees C the Y73H mutation leads to a defect in the synthesis of VPgpUp(U) and of VPg-poly(U) but not in the elongation of a (dT)(15) primer. The double mutant protein had the same activities as Y73H 3D(pol). Using the yeast two-hybrid assay, we detected a reduced interaction between 3D(pol) molecules carrying either the single or double mutations. Tyrosine-73 maps to the finger domain in the three-dimensional structure of 3D(pol). A model will be presented in which a change of Y73 to H73 may interfere with an interaction between two polymerase molecules that, in turn, may interfere with VPg uridylylation. Alternative explanations, however, cannot be excluded at the present time.


Subject(s)
DNA-Directed RNA Polymerases/metabolism , Poliovirus Vaccine, Oral/genetics , Poliovirus/enzymology , RNA-Dependent RNA Polymerase , Viral Core Proteins/metabolism , Amino Acid Sequence , Amino Acid Substitution/genetics , DNA-Directed RNA Polymerases/chemistry , DNA-Directed RNA Polymerases/genetics , DNA-Directed RNA Polymerases/isolation & purification , HeLa Cells , Humans , Hydrogen Bonding , Models, Molecular , Molecular Sequence Data , Mutation/genetics , Phenotype , Poliovirus/genetics , Poliovirus Vaccine, Oral/chemistry , Poly U/biosynthesis , Poly U/genetics , Poly U/metabolism , Protein Binding , Protein Biosynthesis , Protein Conformation , RNA, Messenger/biosynthesis , RNA, Messenger/genetics , RNA, Messenger/metabolism , RNA, Viral/biosynthesis , RNA, Viral/genetics , RNA, Viral/metabolism , Temperature , Transcription, Genetic/genetics , Two-Hybrid System Techniques , Vaccines, Attenuated/chemistry , Vaccines, Attenuated/genetics , Viral Core Proteins/genetics , Viral Plaque Assay
8.
Virus Res ; 62(2): 129-47, 1999 Aug.
Article in English | MEDLINE | ID: mdl-10507323

ABSTRACT

A wealth of experimental data on the mechanism of the picornavirus genome replication has accumulated. Not infrequently, however, conclusions derived from these data appear to contradict each other. On the one hand, initiation of a complementary RNA strand can be demonstrated to occur in a solution containing only the poliovirus RNA polymerase, VPg, uridine triphosphate, poly(A) template and appropriate ions. On the other hand, convincing experiments suggest that efficient initiation of a viral complementary RNA strand requires complex cis-acting signals on the viral RNA template, additional viral and possibly cellular proteins as well as a membrane-containing environment. On the one hand, there is evidence that the viral RNA, in order to be replicated, should first be translated, but on the other hand, the viral RNA polymerase appears to be unable to overcome the ribosome barrier. Possible solutions for these and several other similar paradoxes are discussed, along with less contradictory results on the properties of the picornaviral replicative proteins. Recent results suggesting that recombination and other rearrangements of the viral RNA genomes may be accomplished not only by the replicative template switching but also by nonreplicative mechanisms are also briefly reviewed.


Subject(s)
Genome, Viral , Picornaviridae/genetics , Picornaviridae/metabolism , RNA, Viral/biosynthesis , RNA Helicases/metabolism , RNA-Dependent RNA Polymerase/metabolism , Viral Core Proteins/metabolism
9.
Virology ; 250(1): 241-53, 1998 Oct 10.
Article in English | MEDLINE | ID: mdl-9770438

ABSTRACT

Based on previous studies of dicistronic polioviruses carrying two internal ribosomal entry sites (IRESes), we performed a novel experiment of IRES scanning through a polypeptide by inserting sequentially the IRES of encephalomyocarditis virus into the open reading frame (ORF) of the poliovirus polyprotein at selected 3Cpro-specific Q*G cleavage sites. No cytopathic effects were observed after transfection of HeLa cells with any of the dicistronic constructs, and no virus was recovered. In vitro translation of the dicistronic RNA transcripts in HeLa cell-free extracts revealed that multiple defects in the processing of the P2-P3 domain of the polyprotein is the primary reason for the lethal phenotypes. Surprisingly, the interruption of 3Cpro-catalyzed cleavages downstream of 2C interfered with the 2Apro-catalyzed, primary cleavage between P1 and P2. In contrast, insertion of a foreign coding sequence (V3 loop of human immunodeficiency virus type 1 gp120) into the ORF of the polyprotein at the 2C-3A junction yielded a viable virus that appeared to be genetically stable over several passages. The results of these experiments, which are generally applicable to analyses of viral polyproteins or multidomain polypeptides, suggest that processing of the P2-P3 domain by 3C-3CDpro is rapid and accurate only in the context of the unperturbed P2-P3 precursor; this is consistent with cleavages occurring in cis. Moreover, an intact 2C-3A precursor is not required for viral proliferation.


Subject(s)
5' Untranslated Regions/genetics , Poliovirus/genetics , Protein Precursors/metabolism , Protein Processing, Post-Translational/genetics , Viral Proteins/metabolism , 3C Viral Proteases , Amino Acid Sequence , Cell-Free System , Cysteine Endopeptidases/metabolism , Cytopathogenic Effect, Viral , Encephalomyocarditis virus/genetics , HIV Envelope Protein gp120/genetics , HeLa Cells , Humans , Molecular Sequence Data , Open Reading Frames/genetics , Peptide Fragments/genetics , Poliovirus/enzymology , Protein Precursors/genetics , RNA, Messenger/genetics , RNA, Viral/genetics , Viral Proteins/genetics , Virus Replication
10.
Nature ; 393(6682): 280-4, 1998 May 21.
Article in English | MEDLINE | ID: mdl-9607767

ABSTRACT

A small protein, VPg, is covalently linked to the 5' end of the plus-stranded poliovirus genomic RNA. Poliovirus messenger RNA, identical in nucleotide sequence to genomic RNA, is not capped at its 5' end by the methylated structure that is common to most eukaryotic mRNAs. These discoveries presented two problems. First, as cap structures are usually required for translation of mRNA into protein, how does this uncapped viral RNA act as a template for translation? Second, what is the function of VPg? The identification of the internal ribosomal-entry site, which allows the entry of ribosomes into viral mRNA independently of the 5' mRNA end, has solved the first conundrum. Here we describe the resolution of the second problem. VPg is linked to the genomic RNA through the 5'-terminal uridylic acid of the RNA. We show that VPg can be uridylylated by the poliovirus RNA polymerase 3Dpol. Uridylylated VPg can then prime the transcription of polyadenylate RNA by 3Dpol to produce VPg-linked poly(U). Initiation of transcription of the poliovirus genome from the polyadenylated 3' end therefore depends on VPg.


Subject(s)
DNA-Directed RNA Polymerases/metabolism , Poliovirus/genetics , RNA, Viral/biosynthesis , RNA-Dependent RNA Polymerase , Viral Core Proteins/metabolism , Amino Acid Sequence , DNA-Directed RNA Polymerases/genetics , DNA-Directed RNA Polymerases/isolation & purification , Escherichia coli , Molecular Sequence Data , Poliovirus/enzymology , Poly A/metabolism , Poly U/metabolism , Recombinant Proteins , Transcription, Genetic , Uridine/metabolism , Uridine Triphosphate/metabolism , Viral Core Proteins/chemical synthesis
11.
RNA ; 1(9): 892-904, 1995 Nov.
Article in English | MEDLINE | ID: mdl-8548654

ABSTRACT

Genome replication of poliovirus, as yet unsolved, involves numerous viral polypeptides that arise from proteolysis of the viral polyprotein. One of these proteins is 3AB, an RNA-binding protein with multiple functions, that serves also as the precursor for the genome-linked protein VPg (= 3B). Eight clustered charged amino acid-to-alanine mutants in the 3AB coding region of poliovirus were constructed and analyzed, together with three additional single-amino acid exchange mutants in VPg, for viral phenotypes. All mutants expressed severe inhibition in RNA synthesis, but none were temperature sensitive (ts). The 3AB polypeptides of mutants with a lethal phenotype were overexpressed in Escherichia coli, purified to near homogeneity, and studied with respect to four functions: (1) ribonucleoprotein complex formation with 3CDpro and the 5'-terminal cloverleaf of the poliovirus genome; (2) binding to the genomic and negative-sense RNA; (3) stimulation of 3CDpro cleavage; and (4) stimulation of RNA polymerase activity of 3Dpol. The results have allowed mapping of domains important for RNA binding and the formation of certain protein-protein complexes, and correlation of these processes with essential steps in viral genome replication.


Subject(s)
RNA-Dependent RNA Polymerase , Viral Core Proteins/genetics , Viral Core Proteins/metabolism , Viral Proteins , 3C Viral Proteases , Base Sequence , Cysteine Endopeptidases/metabolism , DNA-Directed RNA Polymerases/metabolism , Escherichia coli/genetics , HeLa Cells/virology , Humans , Molecular Sequence Data , Mutagenesis, Site-Directed , Phenotype , Polymerase Chain Reaction , Protein Biosynthesis , RNA-Binding Proteins/metabolism , Recombinant Proteins/chemistry , Recombinant Proteins/genetics , Recombinant Proteins/metabolism , Ribonucleoproteins/metabolism , Transcription, Genetic , Viral Core Proteins/chemistry , Virus Replication/physiology
12.
J Biol Chem ; 269(46): 29173-81, 1994 Nov 18.
Article in English | MEDLINE | ID: mdl-7961883

ABSTRACT

The synthesis in vitro of poly(U) on a poly(A) template with oligo(dT)15 primer by poliovirus RNA polymerase 3Dpol (280 ng/ml) is strongly stimulated (50-100 fold) by the addition of purified poliovirus polypeptide 3AB. The synthesis of product continues linearly with time for up to 90 min. The reaction with 3Dpol alone can be reactivated and similarly enhanced by the addition of 3AB at 30 min of incubation. Optimal stimulation is achieved under conditions where the concentration of 3Dpol and of template is low, when the molar ratio of 3AB to 3Dpol is about 100:1 and that of 3AB to poly(A) is about 25:1. In the presence of 3AB, the yield of product made by 3Dpol is much increased but its size is unchanged. From a number of basic proteins and peptides tested, a few were found which also exhibited limited enhancement of polymerase activity. The stimulatory effect of 3AB is probably related to its ability to bind both the template-primer, poly(A).oligo(dT)15, and 3Dpol (Molla, A., Harris, K. S., Paul, A. V., Shin, S. H., Mugavero, J., and Wimmer, E. J. (1994) J. Biol. Chem. 269, 27015-27020). RNA synthesis on purified poliovirus RNA with oligo(dT)15 primer is enhanced by 3AB about 5-10 fold, and this reaction is highly sensitive to detergent.


Subject(s)
DNA-Directed RNA Polymerases/metabolism , Poliovirus/enzymology , Poly U/biosynthesis , RNA, Viral/biosynthesis , RNA-Dependent RNA Polymerase , Viral Core Proteins/physiology , Amino Acid Sequence , Base Sequence , Enzyme Activation , Molecular Sequence Data , Oligodeoxyribonucleotides , Poly A/pharmacology , Protein Binding , Thymidine/pharmacology , Viral Core Proteins/isolation & purification
13.
J Biol Chem ; 269(43): 27015-20, 1994 Oct 28.
Article in English | MEDLINE | ID: mdl-7929442

ABSTRACT

Purified recombinant poliovirus polypeptide 3AB interacts with 3CDpro and 3Dpol as shown by coimmunoprecipitation with anti-3Dpol antibodies. A consequence of this interaction is an accelerated autoprocessing of 3CDpro to produce 3Cpro and 3Dpol. The activation of 3Dpol polymerase activity by cleavage of 3CDpro, a polypeptide that has no polymerase activity, can be shown by template- and primer-dependent poly(U) synthesis. Anti-VPg antibodies (VPg = 3B) added to HeLa translation extracts programmed with poliovirion RNA inhibit cleavage of 3CDpro whereas addition of purified 3AB or VPg to these translation reactions increases 3CDpro processing. 3AB stimulates also 3Cpro-related proteolysis of 2BC, a poliovirus-specific, nonstructural processing intermediate. In contrast, 3CDpro-specific cleavage of the structural precursor P1 is inhibited by the addition of 3AB as shown by a decrease in the production of VP0 and VP3. These data shed new light on a phenomenon in the regulation of expression of poliovirus genetic information: whereas the proteinase 3CDpro is needed for processing of the capsid precursor, the cleavage product of this relatively stable precursor is required for RNA replication.


Subject(s)
Cysteine Endopeptidases/metabolism , Poliovirus/growth & development , Protein Precursors/metabolism , Protein Processing, Post-Translational , Viral Core Proteins/metabolism , Viral Proteins , 3C Viral Proteases , Cell-Free System , DNA-Directed RNA Polymerases/metabolism , Enzyme Activation , Genome, Viral , HeLa Cells , Humans , Hydrolysis , Protein Biosynthesis , RNA, Viral/metabolism , Transcription, Genetic , Viral Core Proteins/immunology , Virus Replication
14.
J Biol Chem ; 269(43): 27004-14, 1994 Oct 28.
Article in English | MEDLINE | ID: mdl-7929441

ABSTRACT

Poliovirus proteinase 3CDpro by itself is not an RNA-binding protein. Two cellular proteins have been purified from HeLa cells (p50 and p36) which interact with purified 3CDpro but only p36-3CDpro bind to the 5'-terminal 110 nucleotides of polioviral RNA genome, an RNA segment whose secondary structure resembles a cloverleaf. The identity of these factors was determined by microsequencing tryptic digests of the purified proteins. Host protein p50 is the eukaryotic elongation factor EF-1 alpha, and p36 an N-terminal fragment thereof. p36, referred to as host factor, did not appear to interact with purified 3Cpro or 3Dpol. Significantly, the formation of a 3CDpro-cloverleaf complex was also observed in the presence of purified poliovirus polypeptide 3AB, the precursor of VPg. 3AB by itself does not stably bind to the cloverleaf. Competition experiments have demonstrated that the RNA-protein interactions are specific for the full-length cloverleaf. UV cross-linking studies were employed to examine the protein components of the cloverleaf ribonucleoproteins. RNA footprinting was used to determine the site on the cloverleaf where the viral and cellular factors bind. Finally, we have discovered that 3AB-3CDpro also interacts with the 3'-terminal sequence of poliovirus RNA. In contrast to the 5'-terminal cloverleaf, the 3'-terminal RNA can bind 3AB in the absence of other proteins. A model for initiation of poliovirus RNA synthesis is presented.


Subject(s)
Cysteine Endopeptidases/metabolism , Genome, Viral , Peptide Elongation Factors/metabolism , Poliovirus/metabolism , RNA, Viral/metabolism , Viral Proteins , 3C Viral Proteases , Base Sequence , HeLa Cells , Humans , Models, Genetic , Molecular Sequence Data , Nucleic Acid Conformation , Peptide Elongation Factor 1 , Peptide Elongation Factors/genetics , Peptide Fragments/genetics , Peptide Fragments/metabolism , Poliovirus/growth & development , Protein Binding , RNA-Binding Proteins/metabolism , Sequence Analysis , Viral Core Proteins/metabolism , Virus Replication
15.
Virology ; 199(1): 188-99, 1994 Feb 15.
Article in English | MEDLINE | ID: mdl-8116242

ABSTRACT

Poliovirus protein 2C contains near its N-terminus a putative amphipathic helix which is well conserved among picornaviruses. Three mutants were constructed within this region by site-directed mutagenesis. In the first mutant (pT7XL2-2C-N1) two glutamic acids were replaced with valines at the boundary of the charged and uncharged faces of the helix. The second mutant (pT7XL2-2C-N2) contains an isoleucine to lysine change in the hydrophobic half; in the third mutant (pT7XL2-2C-N3) two lysines were replaced with threonines in the hydrophilic half of the helix. Upon transfection of HeLa cells with RNA transcripts made from these plasmids only pT7XL2-2C-N1 yielded viable virus (W1-2C-N1) which had a small-plaque phenotype. A large-plaque revertant of this virus, W1-2C-N1R, was found to contain the original glutamic acid at one of the mutated sites (E19). There is no detectable minus-stranded RNA synthesis following transfection of HeLa cells with transcript RNAs of the other two plasmids, pT7XL2-2C-N2 and -N3. In vitro translation of these two mutant RNA transcripts in HeLa extracts revealed processing abnormalities in the P2/P3 region of the polyprotein. This leads to a nearly complete absence of 2C and 3AB, which might be the primary cause of defective viral RNA synthesis. The putative amphipathic helix was found to overlap a consensus binding site for double-stranded RNA.


Subject(s)
Carrier Proteins/chemistry , Viral Nonstructural Proteins/chemistry , Amino Acid Sequence , Animals , Base Sequence , Carrier Proteins/genetics , Cloning, Molecular , DNA, Viral , HeLa Cells , Humans , Molecular Sequence Data , Mutagenesis, Site-Directed , Protein Conformation , Transfection , Viral Nonstructural Proteins/genetics , Water/chemistry
16.
J Biol Chem ; 269(1): 66-70, 1994 Jan 07.
Article in English | MEDLINE | ID: mdl-8276867

ABSTRACT

The poliovirus-specific polypeptide 3AB (B = VPg) was expressed in Escherichia coli and purified to near homogeneity. Corresponding to its known association with membranes in poliovirus-infected HeLa cells, 3AB expressed in E. coli was also membrane-associated, and it could be solubilized only in detergent-containing buffers. In soluble form, 3AB was resistant to digestion with the virus-specific proteinases 3Cpro and 3CDpro. However, it was cleaved by these enzymes to 3A and VPg when bound to the bacterial membranes, an observation suggesting that 3AB may deliver the genome-linked protein VPg to the membrane-associated poliovirus replication complex. The specific activity of 3CDpro in processing 3AB was significantly higher than that of 3Cpro. Soluble 3AB was found to stimulate nearly 100-fold poly (A)-dependent, primer-dependent poly(U) synthesis, catalyzed by purified poliovirus RNA polymerase 3Dpol. We propose that 3AB has a dual function in poliovirus genome replication: as a precursor for VPg, and as a co-factor for 3Dpol.


Subject(s)
Cysteine Endopeptidases/metabolism , Poliovirus/metabolism , Viral Core Proteins/metabolism , Viral Proteins , 3C Viral Proteases , Enzyme Activation , HeLa Cells , Humans , Peptides/isolation & purification , Peptides/metabolism , Protein Precursors/metabolism , Protein Processing, Post-Translational , Recombinant Proteins/isolation & purification , Recombinant Proteins/metabolism , Substrate Specificity
17.
J Virol ; 67(10): 5932-8, 1993 Oct.
Article in English | MEDLINE | ID: mdl-8396661

ABSTRACT

The translation and primary processing events of poliovirus polyproteins in HeLa cell extracts were more efficient at 34 degrees C than at 30 or 36 degrees C. The cleavage products of P2 such as 2Apro, 2BC, and 2C appeared early in the reaction before the appearance of the cleavage products of P1 and of 3CDpro, an observation suggesting that P2 was cleaved in cis by 3CDpro. Proteolytic processing of the capsid precursor P1 into VP0, VP1, and VP3 was also more efficient at 34 degrees C than at either 30 or 32 degrees C. Surprisingly, processing of 3CDpro to 3Cpro and 3Dpol was almost completely inhibited at 36 degrees C. The synthesis of virus in the cell extract was greatly enhanced at 34 degrees C over that at 30 or 32 degrees C, whereas incubation at 36 degrees C yielded very little virus. Cerulenin, an inhibitor of lipid synthesis, did not appear to affect virus-specific translation or protein processing, but it almost completely inhibited viral synthesis in vitro. Oleic acid drastically inhibited in vitro translation at 100 microM and in vitro poliovirus synthesis at 25 microM. Addition of HeLa cell smooth membranes partially restored translation but not virus formation. Our observations suggest that in vitro translation, proteolytic processing, and virus formation require intact membranes. Analysis of the in vitro translation products revealed that viral RNA polymerase activity increased linearly during incubation of the translation mixture. RNA polymerase in the crude mixture was inhibited by oleic acid but not by cerulenin. Surprisingly, oleic acid had no direct effect on oligo(U)-primed, poly(A)-dependent poly(U) synthesis catalyzed by purified 3Dpol.


Subject(s)
Cerulenin/pharmacology , Oleic Acids/pharmacology , Poliovirus/physiology , RNA, Viral/biosynthesis , Viral Proteins/biosynthesis , Cell-Free System , Centrifugation, Density Gradient , DNA-Directed RNA Polymerases/metabolism , HeLa Cells , Humans , Kinetics , Oleic Acid , Poliovirus/drug effects , Poliovirus/metabolism , Protein Biosynthesis , Subcellular Fractions/metabolism , Temperature , Virion/drug effects , Virion/metabolism , Virion/physiology
18.
Virology ; 196(2): 739-47, 1993 Oct.
Article in English | MEDLINE | ID: mdl-8396807

ABSTRACT

A dicistronic poliovirus W1-P1/E/P2,3-1 with the genotype [PV]5'NTR-P1-[EMCV]IRES-[PV]P2,3-3'NTR (Molla, Jang, Paul, Reuer, and Wimmer, 1992, Nature 356, 255) was used to investigate whether the viral proteinase 2Apro, whose primary function in proteolytic processing was erased through the insertion of an internal ribosomal entry site (IRES) element into the ORF of the polyprotein, had other function(s) in viral replication. Deletion of 2Apro from W1-P1/E/P2,3-1 rendered the corresponding transcripts unable to replicate whereas partial deletion of 2Apro or an exchange of Cys109 (an amino acid of the catalytic triad of the proteinase) to Ala reduced RNA replication. No cytopathic effects were observed after transfection with any of the three dicistronic constructs containing mutant 2A, and no virus was recovered after attempts to expand a possibly low yield of mutant virus. In contrast, insertion of the IRES of encephalomyocarditis virus (EMCV) into the ORF of the poliovirus polyprotein at the cleavage site between 2Apro and 2B yielded the novel dicistronic virus W1-P1,2A/E/2BC,P3-1 with the genotype [PV]5'NTR-P1-2A-[EMCV]IRES-[PV]2BC-P3-3'NTR, expressing a small plaque phenotype. These results indicate that neither the intact P2 polypeptide nor the cleavage fragment 2AB of P2 is required for viral proliferation. On the other hand, 2Apro appears to be an essential component in RNA replication as no viral RNA synthesis can be observed by reverse transcription/PCR in cells transfected with dicistronic RNA lacking this viral polypeptide.


Subject(s)
Cysteine Endopeptidases/genetics , Genes, Viral/genetics , Poliovirus/growth & development , RNA, Viral/metabolism , Viral Proteins , Viral Structural Proteins/genetics , Virus Replication , Base Sequence , Encephalomyocarditis virus/genetics , Genetic Engineering , HeLa Cells , Humans , Molecular Sequence Data , Mutagenesis, Insertional , Plasmids/genetics , Poliovirus/enzymology , Poliovirus/genetics , Polymerase Chain Reaction , Protein Biosynthesis , Transcription, Genetic , Transfection
19.
Dev Biol Stand ; 78: 39-53, 1993.
Article in English | MEDLINE | ID: mdl-8388831

ABSTRACT

A HeLa cell-free extract has been prepared that efficiently uses full-length poliovirus-specific RNA, transcribed from plasmids with phage T7 RNA polymerase, or poliovirion RNA, for viral protein synthesis in vitro. Extensive proteolytic processing of the polyprotein in the extract produced viral enzymes that led to de novo viral RNA synthesis, and to the formation of infectious particles, as assayed on HeLa cell monolayers. The titre of plaque-forming units (p.f.u.) in the cell-free extract could be increased 70-fold when nucleoside triphosphates were added to the incubation mixture. Formation of infectious material was completely abolished if guanidine hydrochloride, an inhibitor of poliovirus RNA synthesis, but not of viral protein synthesis, was added; it was restored when the template used in the incubation was the RNA of a guanidine-resistant poliovirus mutant. Infectivity was completely inhibited by type-specific neutralizing antisera to poliovirus, and plaques were not formed if the HeLa cell monolayers were first treated with monoclonal antibodies to the poliovirus receptor. These results suggest de novo synthesis of poliovirus in a cell-free extract.


Subject(s)
Cell-Free System , Poliovirus/physiology , RNA, Viral/genetics , Virus Replication , Capsid/biosynthesis , Capsid Proteins , DNA-Directed RNA Polymerases/metabolism , Guanidine , Guanidines/pharmacology , HeLa Cells , Humans , Nucleotides/pharmacology , Poliovirus/immunology , Protein Biosynthesis , RNA, Viral/biosynthesis , Receptors, Virus/immunology , Viral Plaque Assay , Viral Proteins
20.
Nature ; 356(6366): 255-7, 1992 Mar 19.
Article in English | MEDLINE | ID: mdl-1313153

ABSTRACT

High mutation rates have driven RNA viruses to shorten their genomes to the minimum possible size. Mammalian (+)-strand RNA viruses and retroviruses have responded by reducing the number of cis-acting regulatory elements, a constraint that has led to the emergence of the polyprotein. Poliovirus is a (+)-stranded picornavirus whose polyprotein, encoded by an open reading frame spanning most of the viral RNA, is processed by virus-encoded proteinases. Despite their genetic austerity, picornaviruses have retained long 5' untranslated regions, which harbour cis-acting elements that promote initiation of translation independently of the uncapped 5' end of the viral messenger RNA. These elements are termed 'internal ribosomal entry sites' and are formed from highly structured RNA segments of at least 400 nucleotides. How these elements function is not known, but special RNA-binding proteins may be involved. The ribosome or its 40S subunit probably binds at or near a YnXmAUG motif (where Y is a pyrimidine and X is a purine) at the 3' border of the internal ribosomal entry site, which either provides the initiating codon or enables the ribosome to translocate to one downstream (E.W. et al., submitted). Initiation from most eukaryotic messenger RNAs usually occurs by ribosomal recognition of the 5' and subsequent scanning to the AUG codon. Here we describe a genetic strategy for the dissection of polyproteins which proves that an internal ribosomal entry site element can initiate translation independently of the 5' end.


Subject(s)
Genes, Viral , Genetic Engineering , Poliovirus/genetics , RNA, Viral/genetics , Ribosomes/metabolism , Viral Structural Proteins/genetics , Binding Sites , DNA/chemistry , DNA/genetics , HeLa Cells , Humans , Polymerase Chain Reaction , Protein Biosynthesis , RNA, Viral/chemistry , RNA, Viral/metabolism , Transfection , Viral Proteins/biosynthesis
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