Abstract

RecA protein is a DNA-dependent ATPase. RecA protein-mediated ATP hydrolysis occurs throughout the filamentous nucleoprotein complexes of RecA and DNA. Nucleotide analog ATP[γS] may not act simply as a competitive inhibitor, leading to inhibition kinetic patterns that are informative. When a mixture of ATP and ATP[γS] is present at the beginning of reaction, a transient phase lasting several minutes is observed in which the system approaches the state characteristic of the new ATP/ATP[γS] ratio. This phase consists of a burst or lag in ATP hydrolysis, depending on whether ATP or ATP[γS] respectively, is added first. The transition phase reflects a slow conformational change in a RecA monomer or a general adjustment in the structure of RecA filaments. The RecA filaments formed on longer DNA cofactor were more sensitive, and respond more rapidly to ATP[γS] than on shorter DNA cofactors.

• Keywords: adenosine-5′-O-(3-thiotriphosphate); cooperative binding; slow binding inhibitor; DNA-dependent ATPase; RecA protein