Lusetti Shelley L, Hobbs Michael D, Stohl Elizabeth A, Chitteni-Pattu Sindhu, Inman Ross B, Seifert H Steven, Cox Michael M
Department of Biochemistry, University of Wisconsin, Madison, Madison, Wisconsin 53706, USA.
Mol Cell. 2006 Jan 6;21(1):41-50. doi: 10.1016/j.molcel.2005.11.011.
The RecX protein inhibits RecA filament extension, leading to net filament disassembly. The RecF protein physically interacts with the RecX protein and protects RecA from the inhibitory effects of RecX. In vitro, efficient RecA filament formation onto single-stranded DNA binding protein (SSB)-coated circular single-stranded DNA (ssDNA) in the presence of RecX occurs only when all of the RecFOR proteins are present. The RecOR proteins contribute only to RecA filament nucleation onto SSB-coated single-stranded DNA and are unable to counter the inhibitory effects of RecX on RecA filaments. RecF protein uniquely supports substantial RecA filament extension in the presence of RecX. In vivo, RecF protein counters a RecX-mediated inhibition of plasmid recombination. Thus, a significant positive contribution of RecF to RecA filament assembly is to antagonize the effects of the negative modulator RecX, specifically during the extension phase.
RecX蛋白抑制RecA丝的延伸,导致丝的净解聚。RecF蛋白与RecX蛋白发生物理相互作用,并保护RecA免受RecX的抑制作用。在体外,只有当所有RecFOR蛋白都存在时,在RecX存在的情况下,才能在单链DNA结合蛋白(SSB)包被的环状单链DNA(ssDNA)上高效形成RecA丝。RecOR蛋白仅有助于RecA丝在SSB包被的单链DNA上的成核,并且无法对抗RecX对RecA丝的抑制作用。RecF蛋白在RecX存在的情况下独特地支持大量RecA丝的延伸。在体内,RecF蛋白对抗RecX介导的质粒重组抑制。因此,RecF对RecA丝组装的显著正向贡献是拮抗负调节因子RecX的作用,特别是在延伸阶段。