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Article

X-ray Crystal Structure of the Yeast Kar3 Motor Domain Complexed with Mg·ADP to 2.3 Å Resolution^†^,^‡

Andrew M. Gulick,^§ Hebok Song, Sharyn A. Endow, and Ivan Rayment*^§

Institute for Enzyme Research and Department of Biochemistry, University of Wisconsin, Madison, Wisconsin 53705, and Department of Microbiology, Duke University Medical Center, Durham, North Carolina 27710

Biochemistry, 1998, 37 (7), pp 1769–1776

DOI: 10.1021/bi972504o

Publication Date (Web): January 30, 1998

†

This research was supported in part by NIH Grants AR35186 (I.R.) and GM46225 (S.A.E.) and American Cancer Society Grant CB-47 (S.A.E.). A.M.G. was supported by NRSA Fellowship AR08422.

‡

The X-ray coordinates have been deposited in the Brookhaven Protein Data Bank (file name 3KAR).

University of Wisconsin.

Duke University Medical Center.

To whom correspondence should be addressed at Institute for Enzyme Research, 1710 University Ave., Madison, WI 53705. Phone: (608) 262-0529. Fax: (608) 265-2904. E-mail: ivan@enzyme.wisc.edu.

Abstract

The kinesin family of motor proteins, which contain a conserved motor domain of 350 amino acids, generate movement against microtubules. Over 90 members of this family have been identified, including motors that move toward the minus or plus end of microtubules. The Kar3 protein from Saccharomyces cerevisiae is a minus end-directed kinesin family member that is involved in both nuclear fusion, or karyogamy, and mitosis. The Kar3 protein is 729 residues in length with the motor domain located in the C-terminal 347 residues. Recently, the three-dimensional structures of two kinesin family members have been reported. These structures include the motor domains of the plus end-directed kinesin heavy chain [Kull, F. J., et al. (1996) Nature 380, 550−555] and the minus end-directed Ncd [Sablin, E. P., et al. (1996) Nature 380, 555−559]. We now report the structure of the Kar3 protein complexed with Mg·ADP obtained from crystallographic data to 2.3 Å. The structure is similar to those of the earlier kinesin family members, but shows differences as well, most notably in the length of helix α4, a helix which is believed to be involved in conformational changes during the hydrolysis cycle.