TCB Publications - Abstract

Markus Dittrich and Klaus Schulten. PcrA helicase, a prototype ATP-driven molecular motor. Structure, 14:1345-1353, 2006.

DITT2006 Despite extensive studies, the mechanisms underlying molecular motor function are still poorly understood. Key to the mechanisms is the coupling of ATP hydrolysis to conformational changes of the motor protein. To investigate this coupling, we have conducted quantum mechanical/molecular mechanical simulations of PcrA helicase, a strikingly simple motor that translocates uni-directionally along single-stranded DNA (ssDNA). Our results reveal a close similarity in catalytic site structure and reaction pathway to F1-ATPase including a proton relay mechanism important for efficient ATP hydrolysis and an "arginine finger" residue being key to the coupling of the chemical reaction to protein conformational changes. By means of in silico mutation studies, we identified the residue Q254 as being crucial for the coupling of ssDNA translocation to the actual catalytic event. Based on the present result for PcrA helicase and previous findings for F1-ATPase, we propose a general mechanism of ATP-driven molecular motor function.

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