title: The MIA complex is a conserved and novel dynein regulator essential for normal ciliary motility.
abstract: Axonemal dyneins must be precisely regulated and coordinated to produce ordered ciliary/flagellar motility, but how this is achieved is not understood. We analyzed two Chlamydomonas reinhardtii mutants, mia1 and mia2, which display slow swimming and low flagellar beat frequency. We found that the MIA1 and MIA2 genes encode conserved coiled-coil proteins, FAP100 and FAP73, respectively, which form the modifier of inner arms (MIA) complex in flagella. Cryo-electron tomography of mia mutant axonemes revealed that the MIA complex was located immediately distal to the intermediate/light chain complex of I1 dynein and structurally appeared to connect with the nexin-dynein regulatory complex. In axonemes from mutants that lack both the outer dynein arms and the MIA complex, I1 dynein failed to assemble, suggesting physical interactions between these three axonemal complexes and a role for the MIA complex in the stable assembly of I1 dynein. The MIA complex appears to regulate I1 dynein and possibly outer arm dyneins, which are both essential for normal motility.
authors.affiliation: Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA.
authors.forename: Ryosuke
authors.initials: R
authors.lastname: Yamamoto
authors.forename: Kangkang
authors.initials: K
authors.lastname: Song
authors.forename: Haru-Aki
authors.initials: HA
authors.lastname: Yanagisawa
authors.forename: Laura
authors.initials: L
authors.lastname: Fox
authors.forename: Toshiki
authors.initials: T
authors.lastname: Yagi
authors.forename: Maureen
authors.initials: M
authors.lastname: Wirschell
authors.forename: Masafumi
authors.initials: M
authors.lastname: Hirono
authors.forename: Ritsu
authors.initials: R
authors.lastname: Kamiya
authors.forename: Daniela
authors.initials: D
authors.lastname: Nicastro
authors.forename: Winfield S
authors.initials: WS
authors.lastname: Sale
mesh_terms: D000595:Amino Acid Sequence; D054468:Axoneme / Q000378:metabolism; D001483:Base Sequence; D002465:Cell Movement; D016825:Chlamydomonas reinhardtii / Q000166:cytology* / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D002923:Cilia / Q000378:metabolism* / Q000648:ultrastructure; D017124:Conserved Sequence; D004398:Dyneins / Q000737:chemistry / Q000378:metabolism*; D017343:Genes, Plant; D008870:Microtubules / Q000378:metabolism; D008954:Models, Biological; D008958:Models, Molecular; D008969:Molecular Sequence Data; D046912:Multiprotein Complexes / Q000378:metabolism*; D009154:Mutation / Q000235:genetics; D010641:Phenotype; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D058255:Protease Nexins / Q000378:metabolism; D011485:Protein Binding; D055550:Protein Stability; D021381:Protein Transport; D020449:Repetitive Sequences, Amino Acid
chemical_list: D046912:Multiprotein Complexes; D010940:Plant Proteins; D058255:Protease Nexins; D004398:Dyneins