https://scholars.lib.ntu.edu.tw/handle/123456789/625651
標題: | HwMR is a novel magnesium-associated protein | 作者: | Ko L.-N Lim G.Z Chen X.-R Cai C.-J Liu K.-T CHII-SHEN YANG |
公開日期: | 2022 | 來源出版物: | Biophysical Journal | 摘要: | Microbial rhodopsins (MRho) are vital proteins in Haloarchaea for solar light sensing in extreme living environments. Among them, Haloquadratum walsbyi (Hw) is a species known to survive high MgCl2 concentrations, with a total of three MRhos identified, including a high-acid-tolerance light-driven proton outward pump, HwBR, a chloride-insensitive chloride pump, HwHR, and a functionally unknown HwMR. Here, we showed that HwMR is the sole magnesium-sensitive MRho among all tested MRho proteins from Haloarchaea. We identified at least D84 as one of the key residues mediating such magnesium ion association in HwMR. Sequence analysis and molecular modeling suggested HwMR to have an extra H8 helix in the cytosolic region like those in signal-transduction-type MRho of deltarhodopsin-3 (dR-3) and Anabaena sensory rhodopsin (ASR). Further, HwMR showed a distinctly prolonged M-state formation under a high concentration of Mg2+. On the other hand, an H8 helix truncated mutant preserved photocycle kinetics like the wild type, but it led to missing M-state structure. Our findings clearly suggested not only that HwMR is a novel Mg2+-associated protein but that the association with both Mg2+ and the H8 domain stabilizes M-state formation in HwMR. We conclude that Mg2+ association and H8 are crucial in stabilizing HwMR M state, which is a well-known photoreceptor signaling state. © 2022 Biophysical Society |
URI: | https://www.scopus.com/inward/record.uri?eid=2-s2.0-85132537875&doi=10.1016%2fj.bpj.2022.06.010&partnerID=40&md5=5e0fd5fbfcad4110d28523af258f8e44 https://scholars.lib.ntu.edu.tw/handle/123456789/625651 |
ISSN: | 00063495 | DOI: | 10.1016/j.bpj.2022.06.010 |
顯示於: | 生化科技學系 |
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