Identification of the Acidobacterium capsulatum LexA box reveals a lateral acquisition of the Alphaproteobacteria lexA gene.
Acidobacterium capsulatum is the most thoroughly studied species of a new bacterial phylogenetic group designated the phylum Acidobacteria. Through a tblastn search, the A. capsulatum lexA gene has been identified, and its product purified. Electrophoretic mobility shift assays have shown that A. capsulatum LexA protein binds specifically to the direct repeat GTTCN(7)GTTC motif. Strikingly, this is also the LexA box of the Alphaproteobacteria, but had not previously been described outside this subclass of the Proteobacteria. In addition, a phylogenetic analysis of the LexA protein clusters together Acidobacterium and the Alphaproteobacteria, moving the latter away from their established phylogenetic position as a subclass of the Proteobacteria, and pointing to a lateral gene transfer of the lexA gene from the phylum Acidobacteria, or an immediate ancestor, to the Alphaproteobacteria. Lastly, in vivo experiments demonstrate that the A. capsulatum recA gene is DNA-damage inducible, despite the fact that a LexA-binding sequence is not present in its promoter region.
Centre de Recerca en Sanitat Animal (CReSA), Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain.
Gerard
G
Mazón
Centre de Recerca en Sanitat Animal (CReSA), Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain.
Susana
S
Campoy
Biomedical Applications Group, Centro Nacional de Microelectrónica, 08193 Bellaterra, Spain.
Ivan
I
Erill
Departament de Genètica i Microbiologia, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain.|Centre de Recerca en Sanitat Animal (CReSA), Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain.
Jordi
J
Barbé
D020561:Alphaproteobacteria / Q000235:genetics*; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D001665:Binding Sites; D004249:DNA Damage; D004260:DNA Repair; D004269:DNA, Bacterial / Q000235:genetics* / Q000378:metabolism; D004268:DNA-Binding Proteins; D024202:Electrophoretic Mobility Shift Assay; D019143:Evolution, Molecular; D022761:Gene Transfer, Horizontal; D008969:Molecular Sequence Data; D010802:Phylogeny; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D011938:Rec A Recombinases / Q000032:analysis; D013014:SOS Response, Genetics; D017386:Sequence Homology, Amino Acid; D012697:Serine Endopeptidases / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D000099160:LexA Repressor Protein
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D011938:Rec A Recombinases; D012697:Serine Endopeptidases; D000099160:LexA Repressor Protein