The human chromokinesin Kid is a plus end-directed microtubule-based motor.
Kid is a kinesin-like DNA-binding protein known to be involved in chromosome movement during mitosis, although its actual motor function has not been demonstrated. Here, we describe the initial characterization of Kid as a microtubule-based motor using optical trapping microscopy. A bacterially expressed fusion protein consisting of a truncated Kid fragment (amino acids 1-388 or 1-439) is indeed an active microtubule motor with an average speed of approximately 160 nm/s, and the polarity of movement is plus end directed. We could not detect processive movement of either monomeric Kid or dimerizing chimeric Kid; however, low levels of processivity (a few steps) cannot be detected with our method. These results are consistent with Kid having a role in chromosome congression in vivo, where it would be responsible for the polar ejection forces acting on the chromosome arms.
Yajima
Junichiro
J
Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan.
Edamatsu
Masaki
M
Watai-Nishii
Junko
J
Tokai-Nishizumi
Noriko
N
Yamamoto
Tadashi
T
Toyoshima
Yoko Y
YY
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002875:Chromosomes / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D016547:Kinesins / Q000235:genetics / Q000378:metabolism*; D008853:Microscopy / Q000379:methods; D008870:Microtubules / Q000378:metabolism*; D020409:Molecular Motor Proteins / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism*
D004268:DNA-Binding Proteins; C098764:KIF22 protein, human; D020409:Molecular Motor Proteins; D011993:Recombinant Fusion Proteins; D000255:Adenosine Triphosphate; D016547:Kinesins