PMID:12702672
| Citation |
Lanzov, VA, Bakhlanova, IV and Clark, AJ (2003) Conjugational hyperrecombination achieved by derepressing the LexA regulon, altering the properties of RecA protein and inactivating mismatch repair in Escherichia coli K-12. Genetics 163:1243-54 |
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| Abstract |
The frequency of recombinational exchanges (FRE) that disrupt co-inheritance of transferred donor markers in Escherichia coli Hfr by F(-) crosses differs by up to a factor of two depending on physiological factors and culture conditions. Under standard conditions we found FRE to be 5.01 +/- 0.43 exchanges per 100-min units of DNA length for wild-type strains of the AB1157 line. Using these conditions we showed a cumulative effect of various mutations on FRE. Constitutive SOS expression by lexA gene inactivation (lexA71::Tn5) and recA gene mutation (recA730) showed, respectively, approximately 4- and 7-fold increases of FRE. The double lexA71 recA730 combination gave an approximately 17-fold increase in FRE. Addition of mutS215::Tn10, inactivating the mismatch repair system, to the double lexA recA mutant increased FRE to approximately 26-fold above wild-type FRE. Finally, we showed that another recA mutation produced as much SOS expression as recA730 but increased FRE only 3-fold. We conclude that three factors contribute to normally low FRE under standard conditions: repression of the LexA regulon, the properties of wild-type RecA protein, and a functioning MutSHL mismatch repair system. We discuss mechanisms by which the lexA, recA, and mutS mutations may elevate FRE cumulatively to obtain hyperrecombination. |
| Links | |
| Keywords |
Adenosine Triphosphatases/genetics; Bacterial Proteins/genetics; Bacterial Proteins/metabolism; Conjugation, Genetic; DNA Repair; DNA-Binding Proteins; Escherichia coli/genetics; Escherichia coli/metabolism; Escherichia coli Proteins/genetics; Gene Expression Regulation, Bacterial; MutS DNA Mismatch-Binding Protein; Rec A Recombinases/genetics; Rec A Recombinases/metabolism; Serine Endopeptidases/genetics; Serine Endopeptidases/metabolism |
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