Structural and functional domains of the Drosophila ncd microtubule motor protein

• Published in: The Journal of biological chemistry 1993-04, Vol.268 (12), p.9005-9013
• Main Authors: Chandra, R, Salmon, E.D, Erickson, H.P, Lockhart, A, Endow, S.A
• Format: Article
• Language: English
• Subjects: Adenosine Triphosphatases - metabolism; Amino Acid Sequence; Animals; Base Sequence; Biological and medical sciences; Cell structures and functions; Cytoskeleton, cytoplasm. Intracellular movements; DNA; DROSOPHILA; Drosophila - chemistry; Drosophila - metabolism; Drosophila Proteins; Fundamental and applied biological sciences. Psychology; Kinesin; MEIOSE; MEIOSIS; Microtubule Proteins - chemistry; Microtubule Proteins - genetics; Microtubule Proteins - metabolism; Microtubule Proteins - ultrastructure; Microtubules - metabolism; Molecular and cellular biology; Molecular Sequence Data; PROTEINAS; PROTEINE; Recombinant Proteins - isolation & purification; Recombinant Proteins - metabolism
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/s0021-9258(18)52971-9

Nonclaret disjunctional (ncd) is a kinesin-related microtubule motor protein that is required for proper chromosome distribution in Drosophila. Despite its sequence similarity to kinesin heavy chain, ncd translocates with the opposite polarity as kinesin, toward microtubule minus ends. We have expressed different regions of the protein in bacteria and analyzed the proteins for function. Results indicate that ncd consists of three domains: a basic, proline-rich N-terminal "tail," a central alpha-helical coiled-coil stalk, and a C-terminal motor domain. The ncd N terminus proteins bundle microtubules in motility assays and show ATP-independent binding to microtubules in solution. Truncated proteins, lacking the tail but containing the pre-dieted motor domain and differing lengths of the stalk, did not support microtubule gliding in in vitro assays but showed microtubule-stimulated MgATPase activity in solution. Addition of a nonspecific N terminus to two of the truncated proteins restored directional gliding and rotation of microtubules in motility assays, demonstrating that these properties map to the predicted mechanochemical domain of ncd. Physical properties of the C terminus proteins indicate that the stalk region is important for dimerization and that the ncd protein probably exists and functions as a dimer