1p8h
From Proteopedia
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BACTERIORHODOPSIN M1 INTERMEDIATE PRODUCED AT ROOM TEMPERATURE
Overview
An M intermediate of wild-type bacteriorhodopsin and an N intermediate of, the V49A mutant were accumulated in photostationary states at pH 5.6 and, 295 K, and their crystal structures determined to 1.52A and 1.62A, resolution, respectively. They appear to be M(1) and N' in the sequence, M(1)<-->M(2)<-->M'(2)<-->N<-->N'-->O-->BR, where M(1), M(2), and M'(2), contain an unprotonated retinal Schiff base before and after a, reorientation switch and after proton release to the extracellular, surface, while N and N' contain a reprotonated Schiff base, before and, after reprotonation of Asp96 from the cytoplasmic surface. In M(1), we, detect a cluster of three hydrogen-bonded water molecules at Asp96, not, present in the BR state. In M(2), whose structure we reported earlier, one, of these water molecules intercalates between Asp96 and Thr46. In N', the, cluster is transformed into a single-file hydrogen-bonded chain of four, water molecules that connects Asp96 to the Schiff base. We find a network, of three water molecules near residue 219 in the crystal structure of the, non-illuminated F219L mutant, where the residue replacement creates a, cavity. This suggests that the hydration of the cytoplasmic region we, observe in N' might have occurred spontaneously, beginning at an existing, water molecule as nucleus, in the cavities from residue rearrangements in, the photocycle.
About this Structure
1P8H is a Single protein structure of sequence from Halobacterium salinarum with RET, LI1 and SQU as ligands. Full crystallographic information is available from OCA.
Reference
Crystallographic structures of the M and N intermediates of bacteriorhodopsin: assembly of a hydrogen-bonded chain of water molecules between Asp-96 and the retinal Schiff base., Schobert B, Brown LS, Lanyi JK, J Mol Biol. 2003 Jul 11;330(3):553-70. PMID:12842471
Page seeded by OCA on Tue Nov 20 23:35:39 2007
