Developmental changes in ciliary composition during gametogenesis in Chlamydomonas

Chlamydomonas reinhardtii transitions from mitotically dividing vegetative cells to sexually competent gametes of two distinct mating types following nutrient deprivation. Gametes of opposite mating type interact via their cilia, initiating an intraciliary signaling cascade and ultimately fuse forming diploid zygotes. The process of gametogenesis is genetically encoded and a previous study revealed numerous significant changes in mRNA abundance during this life cycle transition. Here we describe a proteomic analysis of cilia derived from vegetative and gametic cells of both mating types in an effort to assess the global changes that occur within the organelle during this process. We identify numerous membrane and/or matrix-associated proteins in gametic cilia that were not detected in cilia from vegetative cells. This includes the pro-protein from which the GATI-amide gametic chemotactic modulator derives, as well as receptors, a dynamin-related protein, ammonium transporters, two proteins potentially involved in the intraciliary signaling cascade-driven increase in cAMP, and multiple proteins with a variety of interaction domains. These changes in ciliary composition likely directly affect the functional properties of this organelle as the cell transitions between life cycle stages.