서강대학교

초록/요약 도움말

Microbial rhodopsin is a seven-transmembrane helix protein that has a retinal as chromophore. Rhodopsins have function as light-driven ion transport, photosensing activities (type I rhodopsin) and function as vision in animal eyes (type II rhodopsin). Proteorhodopsin (PR) is an abundant microbial rhodopsin, which has a function as light-driven proton pumps and was found in many different marine environments. Recently, it has been reported for existence of opsins in non-marine environment with homologous to PR. This study was carried out for further understanding of those partial existing non-marine origin of opsins containing the conserved region sequence of microbial rhodopsin. Ten distinguished partial sequences of opsins homologues from Tonle Sap Great Lake in Cambodia were isolated and constructed chimeric proteins by insertion of those partial sequences to green light absorption proteorhodopsin (GPR) containing N-terminal and C-terminal regions. The partial sequences are containing conserved region between helix C and helix F. The cassette insertion as previous report has called “CFR, Chimeric Freshwater Rhodopsin”. To characterize these chimera freshwater rhodopsin from Tonle Sap (CFR-TS), were overexpressed in E. coli and purified for observing absorption spectra, different spectra, pKa value of proton acceptor, proton pumping activities and photocycle properties. In this study, five partial sequences were characterized and named as CFR-TS1, CFR-TS2, CFR-TS3, CFR-TS4 and CFR-TS5. Those chimeric proteins were studied about their absorbance spectra showing different absorbance spectra (λmax) at 518, 528, 526, 545, and 549 nm, respectively. The other characteristics of those chimeric rhododopsin were alsocharaterized for understanding of the function in freswater.