Characterization of the SOS regulon of Caulobacter crescentus.
The SOS regulon is a paradigm of bacterial responses to DNA damage. A wide variety of bacterial species possess homologs of lexA and recA, the central players in the regulation of the SOS circuit. Nevertheless, the genes actually regulated by the SOS have been determined only experimentally in a few bacterial species. In this work, we describe 37 genes regulated in a LexA-dependent manner in the alphaproteobacterium Caulobacter crescentus. In agreement with previous results, we have found that the direct repeat GTTCN7GTTC is the SOS operator of C. crescentus, which was confirmed by site-directed mutagenesis studies of the imuA promoter. Several potential promoter regions containing the SOS operator were identified in the genome, and the expression of the corresponding genes was analyzed for both the wild type and the lexA strain, demonstrating that the vast majority of these genes are indeed SOS regulated. Interestingly, many of these genes encode proteins with unknown functions, revealing the potential of this approach for the discovery of novel genes involved in cellular responses to DNA damage in prokaryotes, and illustrating the diversity of SOS-regulated genes among different bacterial species.
da Rocha
Raquel Paes
RP
Department of Microbiology, Institute of Biomedical Sciences, São Paulo University, São Paulo, Brazil.
Paquola
Apuã César de Miranda
AC
Marques
Marilis do Valle
Mdo V
Menck
Carlos Frederico Martins
CF
Galhardo
Rodrigo S
RS
D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D016935:Caulobacter crescentus / Q000235:genetics* / Q000378:metabolism; D004249:DNA Damage; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial / Q000528:radiation effects; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D021141:Nucleic Acid Amplification Techniques; D009875:Operator Regions, Genetic / Q000235:genetics; D010641:Phenotype; D011401:Promoter Regions, Genetic / Q000235:genetics; D018085:Regulon / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013014:SOS Response, Genetics / Q000235:genetics*; D012697:Serine Endopeptidases / Q000235:genetics / Q000378:metabolism; D024363:Transcription Initiation Site; D014466:Ultraviolet Rays; D000099160:LexA Repressor Protein
D001426:Bacterial Proteins; D012697:Serine Endopeptidases; D000099160:LexA Repressor Protein