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First published online November 19, 2004; 10.1104/pp.104.052340 Plant Physiology 136:3945-3955 (2004) © 2004 American Society of Plant Biologists A Plant-Specific Kinesin Binds to Actin Microfilaments and Interacts with Cortical Microtubules in Cotton Fibers1Section of Plant Biology, University of California, Davis, California 95616 (M.L.P., Y.-R.J.L., D.P.D., B.L.); and Department of Biological Sciences and Purdue Motility Group, Purdue University, West Lafayette, Indiana 479072064 (D.R.K., C.J.S.)
A novel kinesin, GhKCH1, has been identified from cotton (Gossypium hirsutum) fibers. GhKCH1 has a centrally located kinesin catalytic core, a signature neck peptide of minus end-directed kinesins, and a unique calponin homology (CH) domain at its N terminus. GhKCH1 and other CH domain-containing kinesins (KCHs) belong to a distinct branch of the minus end-directed kinesin subfamily. To date the KCH kinesins have been found only in higher plants. Because the CH domain is often found in actin-binding proteins, we proposed that GhKCH1 might play a role in mediating dynamic interaction between microtubules and actin microfilaments in cotton fibers. In an in vitro actin-binding assay, GhKCH1's N-terminal region including the CH domain interacted directly with actin microfilaments. In cotton fibers, GhKCH1 decorated cortical microtubules in a punctate manner. Occasionally GhKCH1 was found to be associated with transverse-cortical actin microfilaments, but never with axial actin cables in cotton fibers. Localization of GhKCH1 on cortical microtubules was independent of the integrity of actin microfilaments. Thus, GhKCH1 may play a role in organizing the actin network in coordination with the cortical microtubule array. These data also suggest that flowering plants may employ unique KCHs to coordinate actin microfilaments and microtubules during cell growth.
1 This work was supported by the U.S. Department of Energy, Division of Energy Biosciences (grants to B.L., D.P.D., and C.J.S.). 2 Present address: Donald Danforth Plant Science Center, 975 North Warson Road, St. Louis, MO 63132. 3 Present address: Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06520. 4 Present address: The Rockefeller Foundation, 420 Fifth Ave., New York, NY 100182702. Article, publication date, and citation information can be found at www.plantphysiol.org/cgi/doi/10.1104/pp.104.052340. * Corresponding author; e-mail bliu{at}ucdavis.edu; fax 5307525410. Received August 26, 2004; returned for revision October 8, 2004; accepted October 8, 2004. This article has been cited by other articles:
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