Relationship between the functional regions of the RecA protein and ATP hydrolysis in UV-irradiated Escherichia coli cells.
The time course of the intracellular ATP concentration in several UV-irradiated RecA protease constitutive (Cptc) mutants of E. coli has been studied. All Cptc mutants harboring a mutation in region 3 of the RecA protein (including amino acid residues 298-301) increased ATP after UV damage but without any subsequent decrease. Nevertheless, these mutants induced the SOS response after UV irradiation. Likewise, truncated RecA proteins lacking region 3 are also unable to carry out massive ATP hydrolysis in UV-irradiated cells. On the other hand, mutants in region 1 (including amino acids 25-39) or 2 (amino acids 157-184) of the RecA protein showed an increase in ATP concentration during the first 20 min following UV irradiation, which dropped afterwards to the basal level. All these data indicate that region 3 of the RecA protein must be involved in the ATP hydrolysis process. Furthermore, a relationship between the quantity of the UV-mediated ATP produced and the strength of the different RecA Cptc mutants has also been found. Accordingly, both lexA71::Tn5 and null lexA mutants of E. coli only show a cellular ATP increase after UV irradiation when containing a multicopy plasmid carrying either a wild-type lexA or a lexA (Ind-) gene.
Pueyo
M
M
Department of Genetics and Microbiology, Autonomous University of Barcelona, Bellaterra, Spain.
Gibert
I
I
Barbé
J
J
D000255:Adenosine Triphosphate / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects*; D005798:Genes, Bacterial; D006868:Hydrolysis; D009154:Mutation; D010957:Plasmids; D011938:Rec A Recombinases / Q000378:metabolism*; D012697:Serine Endopeptidases; D014466:Ultraviolet Rays; D001616:beta-Galactosidase / Q000235:genetics; D000099160:LexA Repressor Protein
D000255:Adenosine Triphosphate; D001426:Bacterial Proteins; D011938:Rec A Recombinases; D012697:Serine Endopeptidases; D001616:beta-Galactosidase; D000099160:LexA Repressor Protein