Poster: Cytoskeleton structure & dynamics

Abs # 676: Origin and Evolution of Kinesin-like Calmodulin-binding Proteins

Presenter:	Day, Irene S., iday@colostate.edu
Authors	Abdel-Ghany, Salah E. (A)   Day, Irene S. (A)   Simmons, Mark P. (A)   Kugrens, Paul  (A)   Reddy, A.S.N.  (A)
Affiliations:	(A): Colorado State University

KCBP (kinesin-like calmodulin (CaM)-binding protein ) is a C-terminal microtubule motor with three unique domains including a myosin tail homology region 4 (MyTH4), a talin-like domain and a CaM-binding domain. The MyTH4 and talin-like domains (found in some myosins) are not found in any other kinesin reported to date. A kinesin isolated from Strongylocentrotus purpuratus (kinesin-C) is the only reported kinesin with a CaM-binding domain. Analysis of the completed genomes of Homo sapiens, Saccharomyces cerevisiae, Caenorhabditis elegans, and Drosophila melanogaster did not reveal the presence of a KCBP-like kinesin. This prompted us to look at the origin of KCBP and its relationship to kinesin-C. To address this we isolated KCBP from a gymnosperm, Picea abies, and an alga, Stichococcus bacillaris. In addition, database searches resulted in identification of KCBP-like proteins in another alga, Chlamydomonas reinhardtii, several flowering plants and two protozoans ( Tetrahymena thermophila and Giardia lamblia). Gene-tree analysis revealed that the motor domain of all KCBP-like proteins belong to a clade within the kinesin C-terminal subfamily. However, only plant kinesins have been found to contain the MyTH4 and talin-like domains of KCBP whereas kinesin-C from S. purpuratus only has a CaM-binding domain. Our studies indicate that kinesin-C and KCBP may have a common ancestor but that KCBP either gained the MyTH4 and talin-like domains or kinesin-C lost them. Further, our analysis indicates that KCBP is ubiquitous and highly conserved in algae and plants.