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Photochemical chromophore isomerization in histidine kinase rhodopsin HKR1
Author(s) -
Luck Meike,
Bruun Sara,
Keidel Anke,
Hegemann Peter,
Hildebrandt Peter
Publication year - 2015
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 - 10.1016/j.febslet.2015.03.024
Subject(s) - chemistry , isomerization , photochemistry , protonation , chromophore , photoisomerization , deprotonation , photoswitch , rhodopsin , double bond , formylation , histidine , stereochemistry , cis–trans isomerism , cofactor , retinal , organic chemistry , catalysis , biochemistry , enzyme , ion
Histidine kinase rhodopsin 1 is a photoreceptor in green algae functioning as a UV‐light sensor. It switches between a UV‐absorbing state (Rh‐UV) and a blue‐absorbing state (Rh‐Bl) with a protonated retinal Schiff base (RSB) cofactor in a mixture of 13‐ trans ,15‐ anti and 13‐ cis ,15‐ syn isomers. The present spectroscopic study now shows that cofactor‐protein assembly stabilizes the protonated 13‐ trans ,15‐ anti RSB isomer. Formation of the active photoswitch requires the photoinduced conversion to Rh‐UV. The transitions between the Rh‐Bl isomers and the deprotonated 13‐ cis ,15‐ anti and 13‐ trans ,15‐ syn isomers of Rh‐UV proceed via multiple photoisomerizations of one or simultaneously two double bonds.