title: Regulation of monomeric dynein activity by ATP and ADP concentrations.
abstract: Axonemal dyneins are force-generating ATPases that produce ciliary and flagellar movement. A dynein has large heavy chain(s) in which there are multiple (4-6) ATP-binding consensus sequences (P-loops) as well as intermediate and light chains, constituting a very large complex. We purified a monomeric form of dynein (dynein-a) that has at least three light chains from 14S dyneins of Tetrahymena thermophila and characterized it. In in vitro motility assays, dynein-a rotated microtubules around their longitudinal axis as well as translocated them with their plus-ends leading. ATPase activity at 1 mM ATP was doubled in the presence of a low level of ADP (> or = 20 microM). Both ATPase activity and translocational velocities in the presence of ADP (> or = 20 microM) fit the Michaelis-Menten equation well. However, in the absence of ADP (< 0.1 microM), neither of the activities followed the Michaelis-Menten-type kinetics, probably due to the effect of two ATP-binding sites. Our results also indicate that dynein-a has an ATP-binding site that is very sensitive to ADP and affects ATP hydrolysis at the catalytic site. This study shows that a monomeric form of a dynein molecule regulates its activity by direct binding of ATP and ADP to itself, and thus the dynein molecule has an intramolecular regulating system.
authors.affiliation: Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Shiroguchi
authors.forename: Y Y
authors.initials: YY
authors.lastname: Toyoshima
mesh_terms: D000244:Adenosine Diphosphate / Q000378:metabolism*; D000251:Adenosine Triphosphatases / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D001665:Binding Sites; D004398:Dyneins / Q000302:isolation & purification / Q000378:metabolism*; D008870:Microtubules / Q000502:physiology; D009068:Movement / Q000502:physiology; D021381:Protein Transport / Q000502:physiology; D015800:Protozoan Proteins / Q000302:isolation & purification / Q000378:metabolism; D012399:Rotation; D016808:Tetrahymena thermophila / Q000201:enzymology* / Q000378:metabolism
chemical_list: D015800:Protozoan Proteins; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases; D004398:Dyneins