title: Solution structure of two molecular motor domains: nonclaret disjunctional and kinesin.
abstract: The effects of selected ligands on the structure of the truncated heavy-chain chemomechanical motor domains of Drosophila ncd and human kinesin were compared using the technique of transient electric birefringence. The 366-amino acid C-terminal motor domain of Drosophila nonclaret disjunctional, ncd(335-700), and the 349-amino acid N-terminal motor domain of human kinesin, kinesin(349), were studied at 4 degrees C in neutral buffers with ionic strength of 100 mM to form complexes with either MgADP or MgADP.Vi. The rotational diffusion time adjusted to 20 degrees C and water, tau 20,W, for ncd(335-700).MgADP is 32.8 ns, and for ncd(335-700).MgADP.Vi is 34.8 ns, suggesting prolate ellipsoids with dimensions 9.40 x 3.77 nm and 9.73 x 3.70 nm, respectively. The specific Kerr constant, Ksp, of ncd is -1.65 x 10(-12) cm2V-2 for the MgADP complex and -1.15 x 10(-12) cm2V-2 for the MgADP.Vi complex. The large negative Ksp for a prolate protein suggests an unusual charge distribution with two long surfaces with opposite charge. The tau 20,W for kinesin(349).MgADP is longer than the corresponding ncd motor and shows a decrease with increased electric field. The kinesin(349).MgADP.Vi complex has a longer tau 20,W. The Ksp for kinesin(349) is 0.36 x 10(-12) cm2V-2 for each complex.
authors.affiliation: Department of Chemistry and Biochemistry, San Francisco State University 94132, USA.
authors.forename: D
authors.initials: D
authors.lastname: Eden
authors.forename: B Q
authors.initials: BQ
authors.lastname: Luu
authors.forename: D J
authors.initials: DJ
authors.lastname: Zapata
authors.forename: E P
authors.initials: EP
authors.lastname: Sablin
authors.forename: F J
authors.initials: FJ
authors.lastname: Kull
mesh_terms: D000818:Animals; D055592:Biophysical Phenomena; D001703:Biophysics; D001718:Birefringence; D004058:Diffusion; D004330:Drosophila; D029721:Drosophila Proteins; D006801:Humans; D066298:In Vitro Techniques; D016547:Kinesins / Q000737:chemistry* / Q000235:genetics / Q000502:physiology; D008868:Microtubule Proteins / Q000737:chemistry* / Q000235:genetics / Q000502:physiology; D008956:Models, Chemical; D015394:Molecular Structure; D012399:Rotation; D012996:Solutions
chemical_list: D029721:Drosophila Proteins; D008868:Microtubule Proteins; D012996:Solutions; C066696:ncd protein, Drosophila; D016547:Kinesins