RecA and RecX are clearly closely functionally linked. This little subsystem is used to make sure that we get annotations for RecX correct

1: Proc Natl Acad Sci U S A. 2002 Sep 17;99(19):12091-6. Epub 2002 Sep 6.Click here to read
RecX protein abrogates ATP hydrolysis and strand exchange promoted by RecA: insights into negative regulation of homologous recombination.

Venkatesh R, Ganesh N, Guhan N, Reddy MS, Chandrasekhar T, Muniyappa K.


In many eubacteria, coexpression of recX with recA is essential for attenuation of the deleterious effects of recA overexpression; however, the molecular mechanism has remained enigmatic. Here, we show that Mycobacterium tuberculosis RecX binds directly to M. tuberculosis RecA as well as M. smegmatis and E. coli RecA proteins in vivo and in vitro, but not single-stranded DNA binding protein. The direct association of RecX with RecA failed to regulate the specificity or extent of binding of RecA either to DNA or ATP, ligands that are central to activation of its functions. Significantly, RecX severely impeded ATP hydrolysis and the generation of heteroduplex DNA promoted by homologous, as well as heterologous, RecA proteins. These findings reveal a mode of negative regulation of RecA, and imply that RecX might act as an anti-recombinase to quell inappropriate recombinational repair during normal DNA metabolism.

PMID: 12218174

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Proteins. 2009 Feb 1;74(2):530-7.
Crystal structure of RecX: a potent regulatory protein of RecA from Xanthomonas campestris.
Yang CY, Chin KH, Yang MT, Wang AH, Chou SH.


PMID: 19003992