Cohabitation of two different lexA regulons in Pseudomonas putida.
In contrast to the vast majority of the members of the domain Bacteria, several Pseudomonas and Xanthomonas species have two lexA genes, whose products have been shown to recognize different LexA binding motifs, making them an interesting target for studying the interplay between cohabiting LexA regulons in a single species. Here we report an analysis of the genetic composition of the two LexA regulons of Pseudomonas putida KT2440 performed with a genomic microarray. The data obtained indicate that one of the two LexA proteins (LexA1) seems to be in control of the conventional Escherichia coli-like SOS response, while the other LexA protein (LexA2) regulates only its own transcriptional unit, which includes the imuA, imuB, and dnaE2 genes, and a gene (PP_3901) from a resident P. putida prophage. Furthermore, PP_3901 is also regulated by LexA1 and is required for DNA damage-mediated induction of several P. putida resident prophage genes. In silico searches suggested that this marked asymmetry in regulon contents also occurs in other Pseudomonas species with two lexA genes, and the implications of this asymmetry in the evolution of the SOS network are discussed.
Abella
Marc
M
Departament de Genètica i Microbiologia, Ed. Cn, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain.
Campoy
Susana
S
Erill
Ivan
I
Rojo
Fernando
F
Barbé
Jordi
J
D001426:Bacterial Proteins / Q000235:genetics* / Q000502:physiology; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D005814:Genes, Viral; D020411:Oligonucleotide Array Sequence Analysis; D009876:Operon; D039002:Prophages / Q000235:genetics; D016958:Pseudomonas putida / Q000235:genetics* / Q000502:physiology; D018085:Regulon; D013014:SOS Response, Genetics / Q000235:genetics / Q000502:physiology; D012697:Serine Endopeptidases / Q000235:genetics* / Q000502:physiology; D000099160:LexA Repressor Protein
D001426:Bacterial Proteins; D012697:Serine Endopeptidases; D000099160:LexA Repressor Protein