Controlling flagellar strokes

The movements of cilia and flagella are driven by axonemal dynein ATPases, whose activity must be coordinated in space and time. On page 47, Rupp and Porter provide the first molecular characterization of a component of the dynein regulatory complex (DRC), a crucial but poorly understood regulator of flagellar movement. Besides suggesting a model for DRC assembly, the work identifies a possible connection between motility regulation and a theoretical mechanism of cell growth arrest.

Using insertional mutagenesis in Chlamydomonas, the authors identified a new mutation in the PF2 locus that causes motility defects. Further analysis showed that PF2 encodes subunit 4 of the DRC. The PF2 protein is uniformly distributed along the length of the axoneme and also associates with the basal body region, and its predicted structure has several coiled-coil domains that could mediate...