Untitled

Yang, Ming‐Der; Chou, Min-En

doi:10.1007/s002840010214

Cited by 1 publication

(2 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Therefore, although RecX can completely abolish pairing of homologous DNA molecules (joint molecule formation) in vitro at a RecX:RecA molar ratio of 1:44, the RecX:RecA molar ratio inside the bacterial cell is significantly below this, at most 1:300. DNA damage resulted in increased levels of recX transcript in E. coli and other bacteria (11,12,15,31,39). In our studies, after treating E. coli with MMC, RecX and RecA protein levels increased to ϳ800 and 100,000 molecules per cell, respectively (data not shown), so the RecX:RecA ratio is 1:125, which is closer to the level where we saw inhibition of joint molecule formation in vitro.…”

Section: Discussionsupporting

confidence: 80%

“…Because E. coli RecX has potent inhibitory effects on RecA activities both in vitro and in vivo, and because RecX is up-regulated during the SOS response in many bacteria (11,12,15,31,39), this suggests that RecX has some regulatory role during the SOS response, which has yet to be elucidated. The identification of other proteins that modulate RecA activities emphasizes the biological importance of regulating both the SOS response and homologous recombination.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Escherichia coli RecX Inhibits RecA Recombinase and Coprotease Activities in Vitro and in Vivo

Stohl¹,

Brockman²,

Burkle³

et al. 2003

Journal of Biological Chemistry

170

View full text Add to dashboard Cite

In Escherichia coli the RecA protein plays a pivotal role in homologous recombination, DNA repair, and SOS repair and mutagenesis. A gene designated recX (or oraA) is present directly downstream of recA in E. coli; however, the function of RecX is unknown. In this work we demonstrated interaction of RecX and RecA in a yeast two-hybrid assay. In vitro, substoichiometric amounts of RecX strongly inhibited both RecA-mediated DNA strand exchange and RecA ATPase activity. In vivo, we showed that recX is under control of the LexA repressor and is up-regulated in response to DNA damage. A loss-of-function mutation in recX resulted in decreased resistance to UV irradiation; however, overexpression of RecX in trans resulted in a greater decrease in UV resistance. Overexpression of RecX inhibited induction of two din (damage-inducible) genes and cleavage of the UmuD and LexA repressor proteins; however, recX inactivation had no effect on any of these processes. Cells overexpressing RecX showed decreased levels of P1 transduction, whereas recX mutation had no effect on P1 transduction frequency. Our combined in vitro and in vivo data indicate that RecX can inhibit both RecA recombinase and coprotease activities.

show abstract