RESUMO
We described earlier the isolation of lfl25 mutation reducing the frequency of lysogenization of mutant cells by phage lambda (LycA phenotype). The mutation is mapped at present in the rpoC gene coding for the beta' subunit of bacterial RNA polymerase and named rpoC90. It is dominant and causes decrease in pools of some branched amino acids, pyrimidines and thiamine (vitamin B1) in mutant cells. Combination of rpoC90 mutation with some Rif-r mutations strengthens both the LycA phenotype and deficiency in metabolites mentioned above. Such combination was shown to also cause a defect in antitermination (or increases the efficiency of termination) of transcription on the DNA of lambdoid phage phi 434. This defect may indicate the possible mechanism of changes in the regulation of different bacterial operons induced by rpoC90 mutation.
Assuntos
Bacteriófago lambda/genética , Escherichia coli/genética , Genes Bacterianos , Lisogenia , Mutação , Bacteriófago lambda/fisiologia , Escherichia coli/metabolismo , Fator F , PlasmídeosRESUMO
By computer analysis of the lambda phage DNA putative cAMP-CAP binding site has been found. This site (44506-AcgTGTGAccgcatTCAAAaT-44486) is located 40 bp upstream to the late PR' promoter. The sequence denoted is located on the coding DNA strand, similar to the cAMP-CAP binding sites in all four genes known to be subject to cAMP-CAP repression. It is suggested that cAMP-CAP can serve as a repressor of the phage lambda late promoter PR'. Such repression can arrest the expression of late lambda genes and in this way increase the frequency of lysogenization.
Assuntos
Bacteriófago lambda/genética , Sequência de Bases , Proteínas de Transporte/genética , Regiões Promotoras Genéticas , Proteínas Repressoras/genética , Homologia de Sequência do Ácido Nucleico , Fatores de Transcrição/genética , Proteínas de Transporte/metabolismo , AMP Cíclico/metabolismo , DNA Viral/genética , Escherichia coli/genética , Escherichia coli/metabolismo , Proteínas de Ligação ao Cap de RNA , Proteínas Repressoras/metabolismoRESUMO
Lambdoid phage form clear plaques and show reduced ability to establish immunity in LycA mutants of Escherichia coli. This study was undertaken to isolate new LycA mutants. For this purpose, a selective method for isolation of LycA mutants was developed. Two groups of LycA mutants have been isolated and analyzed. It was shown that lysogenization with lambdoid phages may depend on the different bacterial genes.
Assuntos
Escherichia coli/genética , Lisogenia , Mutação , Seleção Genética , Bacteriófago lambda , Genes Bacterianos , Técnicas GenéticasRESUMO
A search-information system has been developed which allows to keep and provide the needed information concerning collections of any microorganisms. The system contains up to 20 000 strains which can be characterized by 4000 properties. The system allows to find all strains corresponding to the given set of characters and also provides the information available for the strain required. The survey of the set of 1000 strains takes as much as 10 sec; the time of search grows linearly with the increase of the strain number. The system is realized on the electronic computer EC1010.
