Curated Optogenetic Publication Database

Abstract: Serotonin (5-HT) signaling is strictly controlled by the serotonin transporter (SERT). The present study aims to establish optogenetic approaches for the control of SERT localization and function by modulating the interaction between SERT and its regulatory protein, soluble guanylate cyclase (sGC). We generated several cell lines that stably express blue light-inducible optogenetic elements fused to sGC or the fourth internal loop (IL4) motif of SERT. Our results indicated that blue light-induced SERT-sGC interaction by heterodimerizing SsrA embedded in the membrane-associated improved light-induced dimer (iLID) and SspB-sGCβ1 decreased SERT localization in the plasma membrane, thus reducing the maximum transport velocity of SERT without affecting its Km for substrate. The light-induced subcellular redistribution of SERT was shown to be attributable to an interference of the SERT-sGC interaction with SERT trafficking but not PKC-mediated internalization. In addition, the light-induced SERT-sGC interaction was blocked by the IL4 peptide or a mutation in the IL4 motif. Furthermore, light-induced exposure of the IL4 motif in iLID decreased the SERT-sGC interaction by displacing SERT from the SERT-sGC complex, thus increasing SERT localization in the membrane and elevating its ability for substrate uptake. This study achieved light-inducible modulation of the protein-protein interaction that allows for the study of biochemical and cellular processes in live cells.

Abstract: Chlamydomonas reinhardtii is an ideal model organism not only for the study of basic metabolic processes in both plants and animals but also the production of biofuels including hydrogen. Transgenic analysis of C. reinhardtii is now well established and very convenient, but inducible exogenous gene expression systems remain under-studied. The most commonly used heat shock-inducible system has serious effects on algal cell growth and is difficult and costly to control in large-scale culture. Previous studies of hydrogen photoproduction in Chlamydomonas also use this heat-inducible system to activate target gene transcription and hydrogen synthesis.