IC138 is a WD-repeat dynein intermediate chain required for light chain assembly and regulation of flagellar bending.
Increased phosphorylation of dynein IC IC138 correlates with decreases in flagellar microtubule sliding and phototaxis defects. To test the hypothesis that regulation of IC138 phosphorylation controls flagellar bending, we cloned the IC138 gene. IC138 encodes a novel protein with a calculated mass of 111 kDa and is predicted to form seven WD-repeats at the C terminus. IC138 maps near the BOP5 locus, and bop5-1 contains a point mutation resulting in a truncated IC138 lacking the C terminus, including the seventh WD-repeat. bop5-1 cells display wild-type flagellar beat frequency but swim slower than wild-type cells, suggesting that bop5-1 is altered in its ability to control flagellar waveform. Swimming speed is rescued in bop5-1 transformants containing the wild-type IC138, confirming that BOP5 encodes IC138. With the exception of the roadblock-related light chain, LC7b, all the other known components of the I1 complex, including the truncated IC138, are assembled in bop5-1 axonemes. Thus, the bop5-1 motility phenotype reveals a role for IC138 and LC7b in the control of flagellar bending. IC138 is hyperphosphorylated in paralyzed flagellar mutants lacking radial spoke and central pair components, further indicating a role for the radial spokes and central pair apparatus in control of IC138 phosphorylation and regulation of flagellar waveform.
Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA.
Triscia W
TW
Hendrickson
Catherine A
CA
Perrone
Paul
P
Griffin
Kristin
K
Wuichet
Joshua
J
Mueller
Pinfen
P
Yang
Mary E
ME
Porter
Winfield S
WS
Sale
D000595:Amino Acid Sequence; D000818:Animals; D002352:Carrier Proteins / Q000737:chemistry / Q000378:metabolism; D002696:Chlamydomonas / Q000201:enzymology*; D003001:Cloning, Molecular; D004398:Dyneins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D005407:Flagella / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D010766:Phosphorylation; D010802:Phylogeny; D010940:Plant Proteins; D017434:Protein Structure, Tertiary; D021122:Protein Subunits / Q000737:chemistry / Q000378:metabolism; D015800:Protozoan Proteins / Q000737:chemistry / Q000378:metabolism; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA
D002352:Carrier Proteins; C492351:LC7 protein, Chlamydomonas; D010940:Plant Proteins; D021122:Protein Subunits; D015800:Protozoan Proteins; D004398:Dyneins