Flagellar quiescence in Chlamydomonas: Characterization and defective quiescence in cells carrying sup‐pf‐1 and sup‐pf‐2 outer dynein arm mutations

Abstract

Chlamydomonas reinhardtii can use their flagella for two distinct types of movement: swimming through liquid or gliding on a solid substrate. Cells switching from swimming to gliding motility undergo a reversible flagellar quiescence. This phenomenon appears to involve the outer dynein arms, since mutants having altered outer arm beta and gamma dyneins (sup-pf-1 and sup-pf-2) show a diminished ability to quiesce. Sup-pf-1 and sup-pf-2 were originally isolated as gain-of-function mutations that suppress the flagellar paralysis resulting from radial spoke or central pair defects. Defective quiescence is also a gain-of-function phenomenon, as cells completely lacking outer arm heavy chains show a normal quiescence phenotype. These data suggest that regulation of outer arm dynein activity is essential for flagellar quiescence and furthermore that regulation of quiescence involves a signal transduction pathway that shares elements with the radial spoke/central pair system.

FAP20 is an inner junction protein of doublet microtubules essential for both the planar asymmetrical waveform and stability of flagella inChlamydomonas

“…To investigate whether all nine DMTs contain FAP20 protein, we frayed the sup-pf1 FAP20-GFP axonemes by protease and ATP treatment. To ensure that the axonemes frayed well, we used a double mutant with a mutant of outer arm dynein, sup-pf1 (Huang et al ., 1982; Porter et al ., 1994; Mitchell et al ., 2004), since its axonemes exhibit enhanced sliding efficiency (our unpublished observation). FAP20-GFP clearly localized to all nine DMTs of the frayed axoneme (Figure 4C).…”

The DPY-30 Domain and Its Flanking Sequence Mediate the Assembly and Modulation of Flagellar Radial Spoke Complexes

“…Another interesting possibility is that this region is part of a swim-to-glide switching mechanism that is calcium dependent and that involves the RS and the CP. When wild-type cells are stuck to the glass, the flagella first become quiescent and then glide along the glass surface (5,36). Perhaps for control cells that manage to swim away the increased intraflagellar calcium from encountering glass alters RSP2/calmodulin interactions and thus modulates the RS/CP control system (Fig.…”

Primary Cilia and the Cell Cycle

“…Although insights into the regulation of cell cycle coordinated ciliary extension and disassembly have emerged from many model systems, most paradigms for these processes have emerged from analysis of the biflagellate, unicellular alga Chlamydomonas reinhardtii (Dutcher, 1995; Haimo and Rosenbaum, 1981; Mitchell et al, 2004; Mitchell and Rosenbaum, 1985; Rosenbaum and Carlson, 1969). Many structural characteristics of the cilia and basal body in Chlamydomonas are identical to those of higher eukaryotes.…”