title: SOS-inducing ability of native and mutant microbial ribonucleases.
abstract: The results of genotoxicity testing of microbial ribonucleases from Bacillus species with different catalytic activity obtained by site-directed mutagenesis in SOS chromotest are reported. At the concentrations 0.1-1 mg/ml, the induction factor for wild-type bacillar binase, barnase and mutant Arg58Lys binase with 100% activity was found to be significantly higher than 1.5 (1.8-2.8). Mutant RNases having decreased catalytic activity (binases with replacements Lys26Ala, Arg61Gln, His101Glu) or through natural inhibitor barstar inactivated wild-type RNase exhibited no SOS-inducing potency. The ability of native bacillar RNases and mutant enzymes possessing high catalytic activity comparable with the activity of wild-type RNase to cause the SOS response indicates that genotoxicity is mediated through the probable cleavage of cellular RNA.
authors.affiliation: GENTOX Laboratory, Microbiology Department, Kazan State University, Tatarstan, Russia. olganil@open.ksu.ras.ru
authors.forename: O N
authors.initials: ON
authors.lastname: Ilinskaya
authors.forename: N S
authors.initials: NS
authors.lastname: Karamova
authors.forename: O B
authors.initials: OB
authors.lastname: Ivanchenko
authors.forename: L V
authors.initials: LV
authors.lastname: Kipenskaya
mesh_terms: D001426:Bacterial Proteins; D004305:Dose-Response Relationship, Drug; D004722:Endoribonucleases / Q000235:genetics / Q000494:pharmacology; D016297:Mutagenesis, Site-Directed; D009152:Mutagenicity Tests / Q000379:methods*; D009154:Mutation; D011994:Recombinant Proteins / Q000494:pharmacology; D012260:Ribonucleases / Q000235:genetics / Q000494:pharmacology*; D013014:SOS Response, Genetics / Q000187:drug effects*; D013329:Structure-Activity Relationship
chemical_list: D001426:Bacterial Proteins; D011994:Recombinant Proteins; D004722:Endoribonucleases; D012260:Ribonucleases; C019760:Bacillus amyloliquefaciens ribonuclease; C022543:ribonuclease T(2)