title: Insight into the mechanism of fast movement of myosin from Chara corallina.
abstract: Chara myosin, two-headed plant myosin belonging to class XI, slides F-actin at maximally 60 microm s(-1). To elucidate the mechanism of this fast sliding, we extensively investigated its mechanochemical properties. The maximum actin activated ATPase activity, Vmax, was 21.3 s(-1) head(-1) in a solution, but when myosin was immobilized on the surface, its activity was 57.6 s(-1) head(-1) at 2 mg ml(-1) of F-actin. The sliding velocity and the actin activated ATPase activity were greatly inhibited by ADP, suggesting that ADP dissociation was the rate limiting step. With the extensive assay of motility by varying the surface density, the duty ratio of Chara myosin was found to be 0.49-0.44 from velocity measurements and 0.34 from the landing rate analysis. At the surface density of 10 molecules microm(-2), Chara myosin exhibited pivot movement under physiological conditions. Based on the results obtained, we will discuss the sliding mechanism of Chara myosin according to the working stroke model in terms of its physiological aspects. aspects.
authors.affiliation: Department of Molecular Biology, School of Science, Nagoya University, Chikusaku Nagoya, Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Sumiyoshi
authors.forename: Masami
authors.initials: M
authors.lastname: Ooguchi
authors.forename: Atsushi
authors.initials: A
authors.lastname: Ooi
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Okagaki
authors.forename: Sugie
authors.initials: S
authors.lastname: Higashi-Fujime
mesh_terms: D000244:Adenosine Diphosphate / Q000494:pharmacology; D000251:Adenosine Triphosphatases / Q000037:antagonists & inhibitors / Q000378:metabolism; D020418:Algal Proteins / Q000502:physiology*; D000818:Animals; D044784:Chara / Q000737:chemistry* / Q000502:physiology; D008747:Methylcellulose / Q000494:pharmacology; D009068:Movement / Q000187:drug effects; D009218:Myosins / Q000502:physiology*; D011817:Rabbits
chemical_list: D020418:Algal Proteins; D000244:Adenosine Diphosphate; D008747:Methylcellulose; D000251:Adenosine Triphosphatases; D009218:Myosins