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1.
Appl Environ Microbiol ; 65(3): 879-85, 1999 Mar.
Article in English | MEDLINE | ID: mdl-10049836
2.
J Bacteriol ; 180(22): 6068-71, 1998 Nov.
Article in English | MEDLINE | ID: mdl-9811672

ABSTRACT

The mmr gene, cloned from Mycobacterium tuberculosis, was shown to confer to Mycobacterium smegmatis resistance to tetraphenylphosphonium (TPP), erythromycin, ethidium bromide, acriflavine, safranin O, and pyronin Y. The gene appears to code for a protein containing four transmembrane domains. Studies of [3H]TPP intracellular accumulation strongly suggest that the resistance mediated by the Mmr protein involves active extrusion of TPP.


Subject(s)
Genes, Bacterial , Mycobacterium tuberculosis/genetics , Amino Acid Sequence , Cloning, Molecular , Coloring Agents , Drug Resistance, Microbial/genetics , Indicators and Reagents , Molecular Sequence Data , Onium Compounds , Organophosphorus Compounds , R Factors , Sequence Analysis, DNA , Tritium
3.
Antimicrob Agents Chemother ; 42(8): 1931-7, 1998 Aug.
Article in English | MEDLINE | ID: mdl-9687386

ABSTRACT

The nucleotide sequence and mechanism of action of a tetracycline resistance gene from Mycobacterium smegmatis were determined. Analysis of a 2.2-kb sequence fragment showed the presence of one open reading frame, designated tet(V), encoding a 419-amino-acid protein (molecular weight, 44,610) with at least 10 transmembrane domains. A database search showed that the gene is homologous to membrane-associated antibiotic efflux pump proteins but not to any known tetracycline efflux pumps. The steady-state accumulation level of tetracycline by M. smegmatis harboring a plasmid carrying the tet(V) gene was about fourfold lower than that of the parental strain. Furthermore, the energy uncoupler carbonyl cyanide m-chlorophenylhydrazone blocked tetracycline efflux in deenergized cells. These results suggest that the tet(V) gene codes for a drug antiporter which uses the proton motive force for the active efflux of tetracycline. By primer-specific amplification the gene appears to be restricted to M. smegmatis and M. fortuitum.


Subject(s)
Genes, Bacterial , Mycobacterium/drug effects , Tetracycline Resistance/genetics , Amino Acid Sequence , Cloning, Molecular , Molecular Sequence Data , Mycobacterium/genetics , Tetracycline/pharmacokinetics
4.
J Gen Microbiol ; 138(7): 1399-408, 1992 Jul.
Article in English | MEDLINE | ID: mdl-1512571

ABSTRACT

The enzyme acetohydroxy acid synthase (AHS), which catalyses the first common step in the biosynthesis of isoleucine, leucine and valine, has been demonstrated to be present in Spirulina platensis in two isoenzymic forms. The complete nucleotide sequences of the genes ilvX and ilvW encoding these two enzymes have been determined. Sequence analysis revealed the presence of two open reading frames, of 1836 and 1737 nucleotides for ilvX and ilvW, respectively. The predicted amino acid sequences of the two isoenzymes, compared with the Synechococcus PCC 7942 AHS enzyme and the large subunits of the Escherichia coli AHSI, II, III isoenzymes, revealed a notable degree of similarity. A small subunit has not been identified for either of the S. platensis AHS isoenzymes. Analysis by Northern blot hybridization demonstrated that the ilvX and ilvW genes are transcribed to give mRNA species of approximately 2.15 kb and 1.95 kb, respectively.


Subject(s)
Acetolactate Synthase/genetics , Cyanobacteria/genetics , Acetolactate Synthase/metabolism , Amino Acid Sequence , Base Sequence , Blotting, Northern , Cyanobacteria/enzymology , DNA, Bacterial , Molecular Sequence Data , Sequence Alignment , Transcription, Genetic
7.
Plant Mol Biol ; 4(2-3): 133-6, 1985 Mar.
Article in English | MEDLINE | ID: mdl-24310750

ABSTRACT

An 8 Kilobase-pair (Kbp) HindIII fragment containing the coding sequence forSpirulina platensis glutamine synthetase [EC 6.3.1.1.] has been identified utilizing a probe derived fromAnabaena 7120 and cloned in the vector pAT153.

8.
J Bacteriol ; 159(1): 407-9, 1984 Jul.
Article in English | MEDLINE | ID: mdl-6330044

ABSTRACT

Probes derived from the tufA gene of Escherichia coli have been utilized to detect homologous sequences on Spirulina platensis DNA. A 6-kilobase-pair fragment of S. platensis DNA appears to contain two sequences homologous to the E. coli gene. Thus, as reported for gram-negative bacteria, the cyanobacterium presumably contains two tuf genes.


Subject(s)
Bacterial Proteins/genetics , Cyanobacteria/genetics , Escherichia coli/genetics , Genes , Base Composition , Base Sequence , DNA Restriction Enzymes , Nucleic Acid Hybridization , Plasmids , Species Specificity
9.
Microbiol Rev ; 47(4): 551-78, 1983 Dec.
Article in English | MEDLINE | ID: mdl-6420655
10.
Eur J Biochem ; 136(2): 241-4, 1983 Nov 02.
Article in English | MEDLINE | ID: mdl-6414811

ABSTRACT

Elongation factor Tu (EF-Tu) has been purified from the cyanobacterium Spirulina platensis. By gel electrophoresis the Mr of the purified protein appears to be 49 000, a value close to that reported for the EF-Tu isolated from a number of bacteria but higher than that reported for the protein isolated from Escherichia coli (43 000). Functionally, however, S. platensis EF-Tu may replace the E. coli protein in a protein-synthesizing system in vitro. In addition, its activity is affected by kirromycin, an antibiotic that specifically interacts with eubacterial EF-Tu.


Subject(s)
Cyanobacteria/metabolism , Peptide Elongation Factors/isolation & purification , Plant Proteins/isolation & purification , Chemical Phenomena , Chemistry , Chromatography/methods , Peptide Elongation Factor Tu
11.
J Bacteriol ; 151(2): 1053-5, 1982 Aug.
Article in English | MEDLINE | ID: mdl-7096264

ABSTRACT

Compared with the parental strain, a Spirulina platensis mutant that is resistant to ethionine incorporated methionine into protein at a reduced rate, whereas ethionine incorporation was practically nil. The methionyl-tRNA synthetase present in crude extracts from the resistant strain showed a reduced affinity for methionine and ethionine.


Subject(s)
Amino Acyl-tRNA Synthetases/metabolism , Cytophagaceae/enzymology , Ethionine/pharmacology , Methionine-tRNA Ligase/metabolism , Cytophagaceae/drug effects , Cytophagaceae/metabolism , Drug Resistance, Microbial , Ethionine/metabolism , Methionine/metabolism , Mutation
12.
J Bacteriol ; 147(3): 1002-7, 1981 Sep.
Article in English | MEDLINE | ID: mdl-6792182

ABSTRACT

Mutants of Spirulina platensis resistant to 5-fluorotryptophan, beta-3-thienyl-alanine, ethionine, p-fluorophenylalanine, or azetidine-2-carboxylic acid were isolated. Some of these mutants appeared to be resistant to more than one analog and to overproduce the corresponding amino acids. A second group was composed of mutants that were resistant to one analog only. Of the latter mutants, one resistant to azetidine-2-carboxylic acid was found to overproduce proline only, whereas one resistant to fluorotryptophan and one resistant to ethionine did not overproduce any of the tested amino acids.


Subject(s)
Cyanobacteria/metabolism , Methionine/biosynthesis , Phenylalanine/biosynthesis , Proline/biosynthesis , Tryptophan/biosynthesis , Alanine/analogs & derivatives , Alanine/pharmacology , Azetidinecarboxylic Acid/pharmacology , Cyanobacteria/drug effects , Drug Resistance, Microbial , Ethionine/pharmacology , Tryptophan/analogs & derivatives , Tryptophan/pharmacology , p-Fluorophenylalanine/pharmacology
14.
Curr Genet ; 2(1): 61-7, 1980 Jul.
Article in English | MEDLINE | ID: mdl-24189724

ABSTRACT

Axenomycin inhibits protein synthesis in vivo and in vitro in Saccharomyces cerevisiae. The antibiotic acts by binding to ribosomes, most probably to the large ribosomal subunit. Mutant strains resistant to axenomycin appear to contain ribosomes that are not inhibited by the antibiotic. The responsible gene has been mapped on the VII chromosome between the centromere and the leu1 gene.

15.
Eur J Biochem ; 102(2): 331-5, 1979 Dec 17.
Article in English | MEDLINE | ID: mdl-118875

ABSTRACT

The elongation factor G (EF-Gchl) and elongation factor Tu (EF-Tuchl) present in spinach chloroplasts become labelled when isolated chloroplasts are incubated in the light with radioactive methionine. EF-Gchl and EF-Tuchl account for approximately 0.04% and 0.2% respectively of the total radioactivity incorporated by isolated organelles.


Subject(s)
Chloroplasts/metabolism , Peptide Elongation Factors/biosynthesis , Electrophoresis, Polyacrylamide Gel , Immunodiffusion , Kinetics , Molecular Weight , Plants/metabolism
16.
Z Naturforsch C Biosci ; 34(12): 1195-8, 1979 Dec.
Article in English | MEDLINE | ID: mdl-161841

ABSTRACT

The light-driven incorporation of amino acids by isolated spinach chloroplasts is inhibited by the M component (VM) and not by the S component (VS) of virginiamycin. This inhibitory effect is partially reversible. In chloroplast extracts, poly(U)-directed polyphenylalanine formation is strongly inhibited by VM and not by VS. The in vivo synergistic effect of VM and VS observed in bacteria and algae, does not occur in isolated chloroplasts and chloroplast extracts.


Subject(s)
Chloroplasts/metabolism , Plant Proteins/biosynthesis , Plants/metabolism , Virginiamycin/pharmacology , Chloroplasts/drug effects , Darkness , Light , Subcellular Fractions/metabolism
17.
Eur J Biochem ; 92(2): 471-7, 1978 Dec.
Article in English | MEDLINE | ID: mdl-738275

ABSTRACT

Elongation factor G (EF-Gchl) and elongation factor Tu (EF-TUchl) have been purified from isolated spinach chloroplasts. On polyacrylamide gel electrophoresis the purifed proteins appear to be at least 70% pure. The molecular weight has been estimated to be 77000 and 45500 for EF-Gchl and EF-TUchl respectively. Chloroplast elongation factor T (EF-Tchl) has been only partially purified. Gel electrophoresis under non-denaturing and denaturing conditons indicate that EF-T-chl is most probably composed of two polypeptides, one of which has an electrophoretic mobility identical to that of EF-TUchl. EF-TUchl appears to represent approximately 7% of the chloroplast soluble protein while EF-Gchl accounts for less than 1%. Just as in the case of the bacterial factors, EF-TUchl appears to be in excess as compared to EF-Gchl. Although no data were obtained on the concentration of EF-Tchl, it may be assumed that the three elongation factors represent approximately 10% of the chloroplast soluble protein.


Subject(s)
Chloroplasts , Peptide Elongation Factors/isolation & purification , Molecular Weight , Peptide Elongation Factors/analysis , Plants
19.
J Bacteriol ; 124(3): 1630-4, 1975 Dec.
Article in English | MEDLINE | ID: mdl-1104596

ABSTRACT

Cells of rough (but not smooth) strains of Salmonella typhimurium become competent for transfection by phage P22 deoxyribonucleic acid after treatment with 0.1 M CaCl2. The yield of infectious centers is about 10(-8) per genome equivalent of deoxyribonucleic acid. However, different sorts of rough strains vary in their ability to become competent in a fashion that can be correlated with the level of the genetic block in cell wall lipopolysaccharide synthesis. The most amenable strains are blocked by defects in the addition of galactose units I and II of the lipopolysaccharide by the inability to synthesize uridine 5'-diphosphate-galactose (galE point mutants and gal deletion mutants). Strains blocked only in the addition of galactose I, glucose I, or heptose II have low levels of transfectability, whereas strains with either more complete or more deficient lipopolysaccharide core are not competent for transfection. When normal lipopolysaccharide synthesis is restored either genetically or by furnishing exogenous galactose (galE point mutants that can still use it), the cells are not longer competent for transfection.


Subject(s)
DNA, Viral , Salmonella Phages , Salmonella typhimurium , Transformation, Genetic , Adsorption , Calcium Chloride/pharmacology , Cell Wall/metabolism , Lipopolysaccharides/biosynthesis , Mutation , Polysaccharides, Bacterial/biosynthesis , Salmonella typhimurium/cytology , Salmonella typhimurium/drug effects , Salmonella typhimurium/metabolism , Temperature , Transformation, Genetic/drug effects , Uridine Diphosphate Galactose/biosynthesis
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