RESUMO
A mutant of Pseudomonas aeruginosa PAO1 originally isolated on the basis of its sensitivity to methyl methanesulphonate was found to be (i) sensitive to u.v.- and gamma-irradiation, (ii)deficient in recombination as assayed by transduction and conjugation and (iii) deficient in an ATP-dependent deoxyribonuclease activity. Its marker (mms-13) is cotransducible with argB and pyrE which are mapped at approximately 22 min on the P. aeruginosa chromosome.
Assuntos
Desoxirribonucleases/deficiência , Pseudomonas aeruginosa/genética , Trifosfato de Adenosina , Mapeamento Cromossômico , Cromossomos Bacterianos , DNA Bacteriano , Marcadores Genéticos , Metanossulfonato de Metila/farmacologia , Mutação , Pseudomonas aeruginosa/enzimologia , Pseudomonas aeruginosa/efeitos da radiação , Recombinação Genética , Transdução GenéticaRESUMO
The effect of R plasmids on spontaneous and radiation (ultraviolet and gamma)-induced mutability in Pseudomonas aeruginosa was studied in strains containing the radiation-sensitive markers polA3 or rec-2 and the revertable auxotrophic markers hisO27 and trpB1. In the absence of an R plasmid, the radiation-induced mutability was dependent on the recA+ genotype and independent of the polA+ genotype, whereas spontaneous mutability was similar in all genetic backgrounds. R plasmids pPL1, R2, and pMG15 increased the ultraviolet radiation survival and ultraviolet-induced mutability of wild-type and polA host cells but did not alter either effect in a recA mutant. These R plasmids also increased the gamma radiation survival and gamma-induced mutability of wild-type host cells bud pMG15 also enhanced the level of spontaneous mutagenesis in wild-type host cells but not in a polA or recA mutant. These data suggested that a common plasmid gene product(s) may participate in various recA-dependent, error-prone deoxyribonucleic acid repair pathways of P. aeruginosa. The properties of a mutant R plasmid, pPL2, originally selected because it lacked enhanced ultraviolet-induced mutability, supported this conclusion.
Assuntos
Reparo do DNA , Mutação/efeitos da radiação , Pseudomonas aeruginosa/efeitos da radiação , Fatores R , Raios Ultravioleta , Alelos , Relação Dose-Resposta à Radiação , Genótipo , Pseudomonas aeruginosa/genética , Pseudomonas aeruginosa/metabolismoRESUMO
Bacteriophage C5 of Pseudomonas aeruginosa is able to reactivate ultraviolet (u.v.)-irradiated phage E79 in coinfection experiments and decrease the u.v.-sensitivity of a host-cell reactivation deficient mutant. These properties suggest that phage C5 has a gene(s) which is involved in the repair of u.v.-damaged DNA. The isolation of two u.v.-sensitive mutants of C5 supports this hypothesis.
