Constitutive and UV-mediated activation of RecA protein: combined effects of recA441 and recF143 mutations and of addition of nucleosides and adenine.
AUTOR(ES)
Sassanfar, M
RESUMO
The recF143 mutant of Escherichia coli is deficient in certain functions that also require the RecA protein: cell survival after DNA damage, some pathways of genetic recombination, and induction of SOS genes and temperate bacteriophage through cleavage of the LexA and phage repressors. To characterize the role of RecF in SOS induction and RecA activation, we determined the effects of the recF143 mutation on the rate of RecA-promoted cleavage of LexA, the repressor of the SOS genes. We show that RecA activation following UV irradiation is delayed by recF143 and that RecF is specifically involved in the SOS induction pathway that requires DNA replication. At 32 degrees C, the recA441 mutation partially suppresses the defect of recF mutants in inducing the SOS system in response to UV irradiation (A. Thomas and R. G. Lloyd, J. Gen. Microbiol. 129:681-686, 1983; M. R. Volkert, L. J. Margossian, and A. J. Clark, J. Bacteriol. 160:702-705, 1984); we find that this suppression occurs at the earliest detectable phase of LexA cleavage and does not require protein synthesis. Our results support the idea that following UV irradiation, RecF enhances the activation of RecA into a form that promotes LexA cleavage (A. Thomas and R. G. Lloyd, J. Gen. Microbiol. 129:681-686, 1983; M. V. V. S. Madiraju, A. Templin, and A. J. Clark, Proc. Natl. Acad. Sci. USA 85:6592-6596, 1988). In contrast to the constitutive activation phenotype of the recA441 mutant, the recA441-mediated suppression of recF is not affected by adenine and nucleosides. We also find that wild-type RecA protein is somewhat activated by adenine in the absence of DNA damage.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=208321Documentos Relacionados
- Two-component suppression of recF143 by recA441 in Escherichia coli K-12.
- Evidence that the recA441 (tif-1) mutant of Escherichia coli K-12 contains a thermosensitive intragenic suppressor of RecA constitutive protease activity.
- recA (Srf) suppression of recF deficiency in the postreplication repair of UV-irradiated Escherichia coli K-12.
- Effect of RecF protein on reactions catalyzed by RecA protein.
- Suppression of the UV-sensitive phenotype of Escherichia coli recF mutants by recA(Srf) and recA(Tif) mutations requires recJ+.