Regulation of RecA Protein Binding to DNA by Opposing Effects of ATP and ADP on Inter-domain Contacts: Analysis by Urea-induced Unfolding of Wild-type and C-terminal Truncated RecA

摘要: RecA protein requires ATP and its hydrolysis to ADP complete the DNA strand-exchange reaction. We investigated how nucleotides activate by examining their effect on urea-induced unfolding, which could reflect domain-domain contact of protein. is folded into three continuous domains: N-terminal, central C-terminal domains. The fluorescence tyrosine residues, lie mainly in domain, was modified 1-3 M urea, while red shift peak tryptophan residues located domain occurred only 3-6 urea. Thus, unfolded after part unfolds. change intensity without a large at low concentrations urea suggests that there are weak interactions between This supported our observation lacking tail lower than entire RecA, with clear transitions, unlike RecA. unhydrolyzable analog (ATPgammaS), enhance binding DNA, facilitated fluorescence, ADP, an antagonist ATP, prevented change. probably weakens facilitates binding, stabilizes inhibits it. Supporting this conclusion, not inhibited intact was.