RESUMO
Mistletoe toxic lectins consist of two polypeptide chains: an enzymatic A chain, the toxic component, is joined by disulfide bond to a B chain conferring the lectin properties to the complete molecules. Mistletoe leaves contain three of toxic lectins encoded by three genes. The three B chains were produced in Escherichia coli in a soluble form. The recombinant proteins were found to bind to asialofetuin but in contrast to native proteins could be competed to a less extent by simple sugars D-galactose and N-acetyl-D-galactosamine. The functional properties of the proteins were strongly influenced by storage conditions such as salt concentration and simple sugar presence thus indicating an unstable folding. The lectin activity of one of the recombinant B chains was most close to the native protein that possibly results from the absence of N-glycosylation.
Assuntos
Erva-de-Passarinho/metabolismo , Lectinas de Plantas/biossíntese , Lectinas de Plantas/química , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/química , Toxinas Biológicas/biossíntese , Toxinas Biológicas/química , Sequência de Aminoácidos , Assialoglicoproteínas/química , Clonagem Molecular , Escherichia coli/genética , Fetuínas , Concentração Inibidora 50 , Erva-de-Passarinho/genética , Dados de Sequência Molecular , Lectinas de Plantas/genética , Plasmídeos/genética , Proteínas Recombinantes/genética , Toxinas Biológicas/genética , alfa-Fetoproteínas/químicaRESUMO
There is a heterogeneous group of plant proteins which are able to enzymatically inactivate ribosomes by depurination of an invariant adenine from the 28 S ribosomal RNA. Some of these proteins are heterodimers having a lectin subunit which is joined by disulfide bond to the enzymatic subunit. Ricin and abrin which are among the most toxic substances known belong to the last group. This review focuses on the structure of the heterodimeric plant ribosome-inactivating proteins, the way of their action on ribosome, biosynthesis, intracellular trafficking, and their possible usage in medicine.
Assuntos
Lectinas de Plantas/metabolismo , Biossíntese de Proteínas/fisiologia , Ribossomos/fisiologia , Abrina/metabolismo , Abrina/farmacologia , Sequência de Aminoácidos , Animais , Dados de Sequência Molecular , Lectinas de Plantas/toxicidade , Biossíntese de Proteínas/efeitos dos fármacos , Inibidores da Síntese de Proteínas/farmacologia , Transporte Proteico , RNA Ribossômico 23S/metabolismo , Ribossomos/efeitos dos fármacos , Ricina/metabolismo , Ricina/farmacologia , Homologia de Sequência de AminoácidosRESUMO
Double-stranded segments (c-ds) have been studied in the poly(A)+ cytoplasmic rat liver RNA. Duplexes about 40 base pairs long have been shown to be of intermolecular character and originate from the interaction between ss-RNA and complementary regions of the poly(A)-containing RNA molecules. Shorter ds-sequences are, mainly, of intramolecular nature. Double-stranded sequences of different length differ also in their oligonucleotide composition, according to fingerprint analysis data. Under the action of cortisone, only several kinds of double-stranded sequences have been demonstrated to increase in the population of cytoplasmic poly(A)+RNA. The function of ds-regions in the hormonal regulation of gene expression is suggested.
Assuntos
Cortisona/análogos & derivados , Fígado/análise , Poli A/análise , RNA de Cadeia Dupla/isolamento & purificação , Animais , Cortisona/farmacologia , Citoplasma/análise , Eletroforese em Gel de Poliacrilamida , Fígado/efeitos dos fármacos , Ácidos Nucleicos Heteroduplexes/isolamento & purificação , Mapeamento de Nucleotídeos , Ratos , Ratos EndogâmicosRESUMO
Oligonucleotide mapping of individual genes was used for search of possible genetic recombinants between natural isolates of influenza H1N1 and H3N2 viruses isolated in the USSR in 1977-1979. No antigenic hybrids and recombinants with the antigenic structure H3N2 were found, however, it was shown that isolates of H1N1 viruses of 1979 (the A/USSR/61/79 strain) might represent genetic recombinants carrying genes P1 + P2 from H3N2 viruses, the M-gene of the USSR/61/79 virus being closest in its structure to the analogous gene of the earliest isolate of H3N2 viruses, namely A/Hong Kong/1/68. Possible selective advantages of virus recombinants having M-genes from viruses of a different serotype are discussed.
Assuntos
Vírus da Influenza A Subtipo H1N1 , Vírus da Influenza A Subtipo H3N2 , Vírus da Influenza A/genética , Recombinação Genética , Genes Virais , Vírus da Influenza A/classificação , Vírus da Influenza A/isolamento & purificação , Mapeamento de Nucleotídeos , Oligonucleotídeos/genética , RNA Viral/genética , SorotipagemRESUMO
Data are presented on structural variability of individual genes of selected variants of epidemic influenza viruses H1N1 (1977-1979) and H3N2 (1968-1979) in the course of antigenic drift obtained by oligonucleotide mapping. Six out of 8 genes of H1N1 viruses were found to be more variable than the corresponding genes of H3N2 viruses. Only HA and NS genes of H3N2 viruses underwent greater structural changes as compared with the analogous genes of H1N1 viruses. In viruses of both serotypes, most variable were the genes coding for hemagglutinin and matrix protein. Possible causes of greater structural variability of the matrix protein gene in the course of antigenic drift are discussed.
Assuntos
Variação Antigênica , Antígenos Virais/genética , Vírus da Influenza A Subtipo H1N1 , Vírus da Influenza A Subtipo H3N2 , Vírus da Influenza A/genética , Antígenos Virais/classificação , Surtos de Doenças , Genes Virais , Humanos , Vírus da Influenza A/classificação , Vírus da Influenza A/imunologia , Vírus da Influenza A/isolamento & purificação , Influenza Humana/microbiologia , Mapeamento de Nucleotídeos , Oligonucleotídeos/análise , RNA Viral/análise , RNA Viral/genética , SorotipagemRESUMO
Changes in structures of only two genes of influenza virus--M and NS genes were found during virus attenuation by the method of oligonucleotide mapping. Such changes were observed in virulent and attenuated viruses (passages 10-23 in chick embryos) by comparing intermediate variants of the virus (passages 11-16 in chick embryos). These results allow us to conclude the important role of these genes in virus attenuation and in connection with virulence of the virus.
Assuntos
Genes Virais , Vírus da Influenza A/genética , RNA Viral/genética , Vírion/genética , Animais , Embrião de Galinha , Eletroforese em Gel de Poliacrilamida , Humanos , Vírus da Influenza A/patogenicidade , Oligonucleotídeos/análise , RNA Viral/análise , Fatores de Tempo , VirulênciaRESUMO
A comparative structural analysis of H1N1 influenza virus isolated in 1977 (the A/USSR/90/77 strain) and H1N1 isolates of 1947 (the A/FM/1/47 strain) and 1950 (the A/FW/1/50 strain) have been carried out by oligonucleotide mapping of individual viral RNA segments. Seven of eight genes of A/USSR/90/77 strain have a high degree of homology with corresponding genes of A/FW/1/50 strain, especially the genes coding the NP and P2 proteins. At the same time the gene coding matrix (M) protein has higher structural similarity to the corresponding gene of A/FM/1/47 strain. Based on the results presented one may conclude that the A/USSR/90/77 epidemic strain is a recombinant virus.
Assuntos
DNA Viral , Genes Virais , Vírus da Influenza A Subtipo H1N1 , Vírus da Influenza A/genética , Oligodesoxirribonucleotídeos/análise , Especificidade da Espécie , Proteínas Virais/genéticaRESUMO
The influenza virus H1N1 (the A/USSR/90/77 strain) that reappeared in 1977 after the H1N1 influenza viruses had disappeared from the human population, is compared with the A/FM/1/47 and the A/FW/1/50 influenza viruses by the method of oligonucleotide mapping of individual segments of the viral RNAs. Seven genes of the A/USSR/90/77 virus appear to be very similar to the corresponding genes of the A/FW/1/50 virus, whereas the gene coding for the M protein displays considerable homology to the corresponding gene of the A/FM/1/47 virus. The data demonstrate that the A/USSR/90/77 strain is a recombinant virus.
