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An Insertion or Deletion in the Extramembrane Loop Connecting Helices E and F of Archaerhodopsin‐1 Affects in vitro Refolding and Slows the Photocycle
Author(s) -
Sugiyama Yasuo,
Koyanagi Takayuki,
Yamada Naohisa,
Mukohata Yasuo
Publication year - 1997
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1997.tb03186.x
Subject(s) - chaps , chemistry , micelle , chromophore , mutant , biophysics , phosphatidylcholine , escherichia coli , rhodopsin , membrane , sodium dodecyl sulfate , pulmonary surfactant , crystallography , stereochemistry , biochemistry , phospholipid , retinal , photochemistry , aqueous solution , biology , gene , organic chemistry
— Upon addition of retinal, archaeopsin‐1 expressed in Escherichia coli ( ec aO‐1002) regenerated the chromophore in dimyristoyl phosphatidylcholine (DMPC), 3‐[(3‐cholamidopropyl) dimethylammonio]‐l‐propanesulfonate (CHAPS) and sodium dodecyl sulfate(SDS) mixed micelles as efficiently as the same opsin prepared from halobacteria. Introduction of an insertion or a deletion of five amino acids into the surface loop connecting helices E and F changed the secondary and tertiary structures of ec aO‐1002 in SDS, and diminished regeneration of the chromophore. The effect of the insertion and deletion on the in vitro refolding was specific to archaeopsin because the same insertion introduced at the corresponding position of bacterioopsin (bO) did not affect chromophore regeneration. The photocycle of the regenerated ec aR‐1002 decreased in DMPC/CHAPS/SDS mixed micelles compared with that of aR‐1 in the claret membrane, which was consistent with the reported behavior of bO. Unexpectedly, the insertion and deletion in loop EF perturbed the photocycle of the regenerated ec aR‐1002. The accumulation of long‐lived N‐ and O‐like intermediates suggested that the insertion and deletion slowed down the proton uptake steps at the cytoplasmic surface.