NOVEL MODE OF HYPER-OSCILLATION IN THE PARALYZED AXONEME OF A CHLAMYDOMONAS MUTANT LACKING THE CENTRAL-PAIR MICROTUBULES

The flagellar axoneme of the mutant pf18 lacking the central pair does not beat, but undergoes a nanometer-scale, high-frequency oscillation (hyper-oscillation) in the presence of ATP [Yagi et al., 1994: Cell M otil. Cytoskeleton 29:177-185]. The present study demonstrates that th e amplitude of the hyper-oscillation increases significantly in the si multaneous presence of ATP and ADP. In addition, the hyper-oscillation under these conditions sometimes takes on an exceptionally simple asy mmetric pattern, in which the maximal shearing velocity exceeds 50 mu m/sec, much higher than the maximal velocity of ordinary dynein-microt ubule sliding. The asymmetric oscillation thus appears to be at least partly driven by an internal elastic force. Its amplitude suggests tha t the axoneme has an elastic component that can be stretched by as lon g as 0.1 mu m. Analyses of the asymmetric pattern further suggests tha t the axonemal dyneins have a tendency to attach to and detach from th e doublets cooperatively and that the mechanochemical cycle of dynein has an inherent refractory period of about 2 msec, during which dynein cannot interact with microtubules. (C) 1995 Wiley-Liss, Inc.