Selective inhibition of RecA functions by the Hc1 nucleoid condensation protein from Chlamydia trachomatis.

During the normal biphasic life cycle of Chlamydia trachomatis, the histone-like protein Hc1 promotes the condensation of nucleoids in elementary bodies, it may also displace nucleoproteins, including repair functions from chromatin. Hc1 was found to effectively inhibit the recombination and repair of the weak binding RecA430 mutant protein from Escherichia coli, but had minimal effects on the parental RecA(+) protein. Expression of Hc1 was also found to inhibit the repair activities of the C. trachomatis RecA protein but not recombination. These results suggest that chlamydial RecA may have evolved mechanisms to minimize Hc1 competition for recombinational activities.