Inhibition of a Mitotic Motor Protein: Where, How, and Conformational Consequences

• Published in: Journal of molecular biology Vol. 335; no. 2; pp. 547 - 554
• Main Authors: Yan, Youwei, Sardana, Vinod, Xu, Bei, Homnick, Carl, Halczenko, Wasyl, Buser, Carolyn A., Schaber, Michael, Hartman, George D., Huber, Hans E., Kuo, Lawrence C.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 09-01-2004
• Subjects: Adenosine Diphosphate - chemistry; Adenosine Diphosphate - metabolism; allosteric inhibition; Binding Sites; Crystallization; Crystallography, X-Ray; Humans; induced-fit; kinesin; Kinesin - antagonists & inhibitors; Kinesin - chemistry; Magnesium - metabolism; Microtubules - chemistry; Mitosis; mitotic arrest; Models, Molecular; Molecular Motor Proteins; Protein Binding - genetics; Protein Conformation; Protein Structure, Tertiary; Pyrimidines - pharmacology; Structure-Activity Relationship; Thiones - pharmacology; X-ray structure; KSP (1–368), the N-terminal 1–368 residues of KSP; allosteric inhibition; mitotic arrest; AMP-PCP, deoxyadenosine 5′-[(phosphonomethyl)phosphonyl phosphate]; TCEP, tri-[2-carboxyethyl]phosphine; kinesin; KSP (1–367H), the N-terminal 1–367 residues of KSP linked with a His 6 tag on its C terminus; induced-fit; X-ray structure
• ISSN: 0022-2836; 1089-8638
• DOI: 10.1016/j.jmb.2003.10.074

We report here the first inhibitor-bound structure of a mitotic motor protein. The 1.9
Å resolution structure of the motor domain of KSP, bound with the small molecule monastrol and Mg
2+·ADP, reveals that monastrol confers inhibition by “induced-fitting” onto the protein some 12
Å away from the catalytic center of the enzyme, resulting in the creation of a previously non-existing binding pocket. The structure provides new insights into the biochemical and mechanical mechanisms of the mitotic motor domain. Inhibition of KSP provides a novel mechanism to arrest mitotic spindle formation, a target of several approved and investigative anti-cancer agents. The structural information gleaned from this novel pocket offers a new angle for the design of anti-mitotic agents.