FG 1261/2: Functional Characterization of Channelrhodopsins and Enzymerhodopsins in Chlamydomonas Reinhardtii (SP 02)

To fully understand the differential in vivo function of the two directly light-gated ion channels in Chlamydomonas, channelrhodopsin-1 and 2 (ChR1 and ChR2), we need transformants with completely inactivated CHR1 and CHR2 genes. Provided, these strains can be functionally complemented, in the next step we will complement with ChR1/ChR2 analogs that differ in absorption, ion specificity, and photocycle kinetics. In the second part of the project, the location of recently discovered rhodopsins with putative C-terminal cyclase activity (enzyme?rhodopsins, CR5 and CR6) will be studied by fluorescence imaging. The function will be analyzed in vegetative cells, gametes and zygotes of wild type and RNAi-strains by applying light scattering, phototaxis assays or photocurrent recording from single cells. The contribution of enzyme rhodopsins to internal Ca2+ turnover, pH, gene expression, circadian rhythm and developmental processes will be studied by applying different imaging techniques. Moreover, the function of the enzymerhodopsins will be discriminated from those of other photoreceptors in strains with inactivated photoreceptor genes.