Lessons learned from UvrD helicase: mechanism for directional movement.
How do molecular motors convert chemical energy to mechanical work? Helicases and nucleic acids offer simple motor systems for extensive biochemical and biophysical analyses. Atomic resolution structures of UvrD-like helicases complexed with DNA in the presence of AMPPNP, ADP.Pi, and Pi reveal several salient points that aid our understanding of mechanochemical coupling. Each ATPase cycle causes two motor domains to rotationally close and open. At a minimum, two motor-track contact points of alternating tight and loose attachment convert domain rotations to unidirectional movement. A motor is poised for action only when fully in contact with its track and, if applicable, working against a load. The orientation of domain rotation relative to the track determines whether the movement is linear, spiral, or circular. Motors powered by ATPases likely deliver each power stroke in two parts, before and after ATP hydrolysis. Implications of these findings for analyzing hexameric helicase, F(1)F(0) ATPase, and kinesin are discussed.
Yang
Wei
W
Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA. wei.yang@nih.gov
D000251:Adenosine Triphosphatases / Q000378:metabolism; D004265:DNA Helicases / Q000737:chemistry* / Q000378:metabolism*; D004734:Energy Metabolism; D004926:Escherichia coli / Q000201:enzymology*; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000378:metabolism*; D020409:Molecular Motor Proteins / Q000737:chemistry / Q000378:metabolism
D029968:Escherichia coli Proteins; D020409:Molecular Motor Proteins; D000251:Adenosine Triphosphatases; C506746:UvrD protein, E coli; D004265:DNA Helicases