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Low‐temperature Raman spectroscopy reveals small chromophore distortion in primary photointermediate of proteorhodopsin
Author(s) -
Fujisawa Tomotsumi,
Abe Masahiro,
Tamogami Jun,
Kikukawa Takashi,
Kamo Naoki,
Unno Masashi
Publication year - 2018
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1002/1873-3468.13219
Subject(s) - bacteriorhodopsin , haloarchaea , chromophore , raman spectroscopy , proton , photochemistry , rhodopsin , spectroscopy , chemistry , materials science , optics , physics , retinal , biochemistry , quantum mechanics , membrane , archaea , gene
Proteorhodopsin ( PR ) is a microbial rhodopsin functioning as a light‐driven proton pump in aquatic bacteria. We performed low‐temperature Raman measurements of PR to obtain the structure of the primary photoproduct, the K intermediate ( PR K ). PR K showed the hydrogen‐out‐of‐plane modes that are much less intense than those of bacteriorhodopsin as the prototypical light‐driven proton pump from haloarchaea. The present results reveal the significantly relaxed chromophore structure in PR K , which can be coupled to the slow kinetics of the K intermediate. This structure suggests that PR transports protons using the small energy storage within the chromophore at the start of its photocycle.