title: Microscopic evidence for a minus-end-directed power stroke in the kinesin motor ncd.
abstract: We used cryo-electron microscopy and image reconstruction to investigate the structure and microtubule-binding configurations of dimeric non-claret disjunctional (ncd) motor domains under various nucleotide conditions, and applied molecular docking using ncd's dimeric X-ray structure to generate a mechanistic model for force transduction. To visualize the alpha-helical coiled-coil neck better, we engineered an SH3 domain to the N-terminal end of our ncd construct (296-700). Ncd exhibits strikingly different nucleotide-dependent three-dimensional conformations and microtubule-binding patterns from those of conventional kinesin. In the absence of nucleotide, the neck adapts a configuration close to that found in the X-ray structure with stable interactions between the neck and motor core domain. Minus-end-directed movement is based mainly on two key events: (i) the stable neck-core interactions in ncd generate a binding geometry between motor and microtubule which places the motor ahead of its cargo in the minus-end direction; and (ii) after the uptake of ATP, the two heads rearrange their position relative to each other in a way that promotes a swing of the neck in the minus-end direction.
authors.affiliation: European Molecular Biology Laboratory, Structure Programme, Meyerhofstrasse 1, D-69117 Heidelberg, Germany.
authors.forename: Thomas G
authors.initials: TG
authors.lastname: Wendt
authors.forename: Niels
authors.initials: N
authors.lastname: Volkmann
authors.forename: Georgios
authors.initials: G
authors.lastname: Skiniotis
authors.forename: Kenneth N
authors.initials: KN
authors.lastname: Goldie
authors.forename: Jens
authors.initials: J
authors.lastname: Müller
authors.forename: Eckhard
authors.initials: E
authors.lastname: Mandelkow
authors.forename: Andreas
authors.initials: A
authors.lastname: Hoenger
mesh_terms: D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D020285:Cryoelectron Microscopy; D029721:Drosophila Proteins / Q000502:physiology / Q000648:ultrastructure*; D007091:Image Processing, Computer-Assisted; D016547:Kinesins / Q000502:physiology / Q000648:ultrastructure*; D008870:Microtubules / Q000378:metabolism; D008958:Models, Molecular; D020409:Molecular Motor Proteins / Q000737:chemistry* / Q000502:physiology; D009068:Movement; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000502:physiology / Q000648:ultrastructure; D008941:Spindle Apparatus; D013329:Structure-Activity Relationship; D014404:Tubulin / Q000378:metabolism
chemical_list: D029721:Drosophila Proteins; D020409:Molecular Motor Proteins; D011993:Recombinant Fusion Proteins; D014404:Tubulin; C066696:ncd protein, Drosophila; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D016547:Kinesins