Nucleotide-dependent movements of the kinesin motor domain predicted by simulated annealing.
The structure of an ATP-bound kinesin motor domain is predicted and conformational differences relative to the known ADP-bound form of the protein are identified. The differences should be attributed to force-producing ATP hydrolysis. Candidate ATP-kinesin structures were obtained by simulated annealing, by placement of the ATP gamma-phosphate in the crystal structure of ADP-kinesin, and by interatomic distance constraints. The choice of such constraints was based on mutagenesis experiments, which identified Gly-234 as one of the gamma-phosphate sensing residues, as well as on structural comparison of kinesin with the homologous nonclaret disjunctional (ncd) motor and with G-proteins. The prediction of nucleotide-dependent conformational differences reveals an allosteric coupling between the nucleotide pocket and the microtubule binding site of kinesin. Interactions of ATP with Gly-234 and Ser-202 trigger structural changes in the motor domain, the nucleotide acting as an allosteric modifier of kinesin's microtubule-binding state. We suggest that in the presence of ATP kinesin's putative microtubule binding regions L8, L12, L11, alpha4, alpha5, and alpha6 form a face complementary in shape to the microtubule surface; in the presence of ADP, the microtubule binding face adopts a more convex shape relative to the ATP-bound form, reducing kinesin's affinity to the microtubule.
Department of Physics and Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 USA.
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D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism*; D000595:Amino Acid Sequence; D002151:Calorimetry; D003198:Computer Simulation; D017124:Conserved Sequence; D018360:Crystallography, X-Ray; D006860:Hydrogen Bonding; D006863:Hydrogen-Ion Concentration; D016547:Kinesins / Q000737:chemistry* / Q000378:metabolism*; D007700:Kinetics; D008870:Microtubules / Q000502:physiology; D008958:Models, Molecular; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D014867:Water
D014867:Water; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D016547:Kinesins