title: Partially functional outer-arm dynein in a novel Chlamydomonas mutant expressing a truncated gamma heavy chain.
abstract: The outer dynein arm of Chlamydomonas flagella contains three heavy chains (alpha, beta, and gamma), each of which exhibits motor activity. How they assemble and cooperate is of considerable interest. Here we report the isolation of a novel mutant, oda2-t, whose gamma heavy chain is truncated at about 30% of the sequence. While the previously isolated gamma chain mutant oda2 lacks the entire outer arm, oda2-t retains outer arms that contain alpha and beta heavy chains, suggesting that the N-terminal sequence (corresponding to the tail region) is necessary and sufficient for stable outer-arm assembly. Thin-section electron microscopy and image analysis localize the gamma heavy chain to a basal region of the outer-arm image in the axonemal cross section. The motility of oda2-t is lower than that of the wild type and oda11 (lacking the alpha heavy chain) but higher than that of oda2 and oda4-s7 (lacking the motor domain of the beta heavy chain). Thus, the outer-arm dynein lacking the gamma heavy-chain motor domain is partially functional. The availability of mutants lacking individual heavy chains should greatly facilitate studies on the structure and function of the outer-arm dynein.
authors.affiliation: Department of Biological Sciences, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Zhongmei
authors.initials: Z
authors.lastname: Liu
authors.forename: Hiroko
authors.initials: H
authors.lastname: Takazaki
authors.forename: Yuki
authors.initials: Y
authors.lastname: Nakazawa
authors.forename: Miho
authors.initials: M
authors.lastname: Sakato
authors.forename: Toshiki
authors.initials: T
authors.lastname: Yagi
authors.forename: Takuo
authors.initials: T
authors.lastname: Yasunaga
authors.forename: Stephen M
authors.initials: SM
authors.lastname: King
authors.forename: Ritsu
authors.initials: R
authors.lastname: Kamiya
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D000818:Animals; D015153:Blotting, Western; D002696:Chlamydomonas / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics / Q000502:physiology; D004398:Dyneins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D005407:Flagella / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics / Q000502:physiology; D009154:Mutation; D021122:Protein Subunits / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D015800:Protozoan Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D021122:Protein Subunits; D015800:Protozoan Proteins; D000251:Adenosine Triphosphatases; D004398:Dyneins