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Publication Abstract from PubMed

The K intermediate of proton pumping bacteriorhodopsin is the first intermediate generated after isomerization of retinal to the 13-cis form. Although various structures have been reported for the K intermediate until now, these differ from each other, especially in terms of the conformation of the retinal chromophore and its interaction with surrounding residues. We report here an accurate X-ray crystallographic analysis of the K structure. The polyene chain of 13-cis retinal is observed to be S-shaped. The side chain of Lys216, which is covalently bound to retinal via the Schiff-base linkage, interacts with residues, Asp85 and Thr89. In addition, the Nzeta-H of the protonated Schiff-base linkage interacts with a residue, Asp212 and a water molecule, W402. Based on quantum chemical calculations for this K structure, we examine the stabilizing factors of distorted conformation of retinal and propose a relaxation manner to the next L intermediate.

Detailed analysis of distorted retinal and its interaction with surrounding residues in the K intermediate of bacteriorhodopsin.,Taguchi S, Niwa S, Dao HA, Tanaka Y, Takeda R, Fukai S, Hasegawa K, Takeda K Commun Biol. 2023 Feb 17;6(1):190. doi: 10.1038/s42003-023-04554-2. PMID:36808185^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.