Optical Control Of Cgmp Signaling

Zoospores of the aquatic fungi Blastocladiella emersonii are phototactic and a rhodopsin-guanylyl cyclase (RhGC) was identified as the putative phototaxis receptor. Due to the direct linkage between the rhodopsin and the cyclase domain, RhGC represents the first member of a novel class of enzyme linked rhodopsins. In this work, we characterized RhGC biophysically. We show that green light maximally activates RhGC and cyclic GMP is produced. After a short green laser flash, RhGC (D525) converts in 8 ms into a blue-shifted signaling state P380 and recovers within 100 ms. RhGC expresses well in Xenopus oocytes, yeast, CHO cells, mammalian neurons and cyclic GMP production was light dose-dependent, rapid and reproducible. Thus, RhGC is a versatile tool for optogenetic analysis of cGMP-dependent signaling processes in cell biology and the neurosciences.