title: An alkB gene homolog is differentially transcribed during the Caulobacter crescentus cell cycle.
abstract: A Caulobacter crescentus alkB gene homolog was identified in a clone previously shown to contain the heat shock genes dnaK and dnaJ; the homolog is located upstream of dnaK and is transcribed in the opposite orientation. An analysis of the alkB gene has shown that the deduced amino acid sequence is that of a 21-kDa protein, which is 42% identical and 78% similar to Escherichia coli AlkB. Furthermore, an alkB-null mutant was constructed by gene disruption and was shown to be highly sensitive to the alkylating agent methyl methanesulfonate (MMS). However, the alkB gene of C. crescentus, unlike its E. coli counterpart, is not located downstream of the ada gene, and its transcription is not induced by alkylating agents. In addition, no acquired enhanced resistance to MMS toxicity by treatment with low MMS doses was observed, suggesting that no adaptive response occurs in C. crescentus. Nevertheless, transcription of the alkB gene is cell cycle controlled, with a pattern of expression similar to that of several Caulobacter genes involved in DNA replication.
authors.affiliation: Departamento de Bioquimica, Instituto de Quimica, Universidade de Sao Paulo, Brazil.
authors.forename: D
authors.initials: D
authors.lastname: Colombi
authors.forename: S L
authors.initials: SL
authors.lastname: Gomes
mesh_terms: D000222:Adaptation, Physiological / Q000187:drug effects; D000477:Alkylating Agents / Q000494:pharmacology; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000187:drug effects / Q000235:genetics; D001483:Base Sequence; D016935:Caulobacter crescentus / Q000166:cytology / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics*; D002453:Cell Cycle / Q000187:drug effects / Q000235:genetics*; D042926:Cytochrome P-450 CYP4A; D003577:Cytochrome P-450 Enzyme System / Q000096:biosynthesis / Q000187:drug effects / Q000235:genetics*; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D005798:Genes, Bacterial / Q000187:drug effects; D008741:Methyl Methanesulfonate / Q000494:pharmacology; D006899:Mixed Function Oxygenases / Q000096:biosynthesis / Q000187:drug effects / Q000235:genetics*; D008969:Molecular Sequence Data; D009154:Mutation; D017422:Sequence Analysis, DNA; D014158:Transcription, Genetic / Q000187:drug effects
chemical_list: D000477:Alkylating Agents; D001426:Bacterial Proteins; D003577:Cytochrome P-450 Enzyme System; D008741:Methyl Methanesulfonate; D006899:Mixed Function Oxygenases; D042926:Cytochrome P-450 CYP4A