An outer arm dynein light chain acts in a conformational switch for flagellar motility.
A system distinct from the central pair-radial spoke complex was proposed to control outer arm dynein function in response to alterations in the mechanical state of the flagellum. In this study, we examine the role of a Chlamydomonas reinhardtii outer arm dynein light chain that associates with the motor domain of the gamma heavy chain (HC). We demonstrate that expression of mutant forms of LC1 yield dominant-negative effects on swimming velocity, as the flagella continually beat out of phase and stall near or at the power/recovery stroke switchpoint. Furthermore, we observed that LC1 interacts directly with tubulin in a nucleotide-independent manner and tethers this motor unit to the A-tubule of the outer doublet microtubules within the axoneme. Therefore, this dynein HC is attached to the same microtubule by two sites: via both the N-terminal region and the motor domain. We propose that this gamma HC-LC1-microtubule ternary complex functions as a conformational switch to control outer arm activity.
Patel-King
Ramila S
RS
Department of Molecular, Microbial, and Structural Biology, University of Connecticut Health Center, Farmington, CT 06030, USA.
King
Stephen M
SM
D000818:Animals; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002465:Cell Movement / Q000502:physiology*; D016825:Chlamydomonas reinhardtii / Q000166:cytology / Q000502:physiology; D029721:Drosophila Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004398:Dyneins; D005407:Flagella / Q000378:metabolism / Q000648:ultrastructure; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D010641:Phenotype; D017434:Protein Structure, Tertiary; D015800:Protozoan Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014404:Tubulin / Q000378:metabolism
D002352:Carrier Proteins; D029721:Drosophila Proteins; D015800:Protozoan Proteins; D014404:Tubulin; D004398:Dyneins