title: The microtubule-destabilizing kinesin XKCM1 is required for chromosome positioning during spindle assembly.
abstract: Xenopus kinesin catastrophe modulator-1 (XKCM1) is a Kin I kinesin family member that uses the energy of ATP hydrolysis to depolymerize microtubules. We demonstrated previously that XKCM1 is essential for mitotic-spindle assembly in vitro and acts by regulating microtubule dynamics as a pure protein, in extracts and in cells. A portion of the XKCM1 pool is specifically localized to centromeres during mitosis and may be important in chromosome movement. To selectively analyze the function of centromere-bound XKCM1, we generated glutathione-S-transferase (GST) fusion proteins containing the N-terminal globular domain (GST-NT), the centrally located catalytic domain (GST-CD), and the C-terminal alpha-helical tail (GST-CT) of XKCM1. The GST-NT protein targeted to centromeres during spindle assembly, suggesting that the N-terminal domain of XKCM1 is sufficient for centromere localization. Addition of GST-NT prior to or after spindle assembly replaced endogenous XKCM1, indicating that centromere targeting is a dynamic process. Loss of endogenous XKCM1 from centromeres caused a misalignment of chromosomes on the metaphase plate without affecting global spindle structure. These results suggest that centromere bound XKCM1 has an important role in chromosome positioning on the spindle.
authors.affiliation: Medical Sciences, Indiana University, Bloomington, IN 47405, USA. cwalczak@indiana.edu
authors.forename: Claire E
authors.initials: CE
authors.lastname: Walczak
authors.forename: Eugene C
authors.initials: EC
authors.lastname: Gan
authors.forename: Arshad
authors.initials: A
authors.lastname: Desai
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Mitchison
authors.forename: Susan L
authors.initials: SL
authors.lastname: Kline-Smith
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002503:Centromere; D005982:Glutathione Transferase / Q000378:metabolism; D016547:Kinesins / Q000502:physiology*; D008969:Molecular Sequence Data; D017386:Sequence Homology, Amino Acid; D008941:Spindle Apparatus; D014981:Xenopus; D029867:Xenopus Proteins / Q000502:physiology*
chemical_list: C088335:KIF11 protein, Xenopus; D029867:Xenopus Proteins; D005982:Glutathione Transferase; D016547:Kinesins