1FBK: CRYSTAL STRUCTURE OF CYTOPLASMICALLY OPEN CONFORMATION OF BACTERIORHODOPSIN

Citation:
Abstract
Bacteriorhodopsin, a membrane protein with a relative molecular mass of 27,000, is a light driven pump which transports protons across the cell membrane of the halophilic organism Halobacterium salinarum. The chromophore retinal is covalently attached to the protein via a protonated Schiff base. Upon illumination, retinal is isomerized. The Schiff base then releases a proton to the extracellular medium, and is subsequently reprotonated from the cytoplasm. An atomic model for bacteriorhodopsin was first determined by Henderson et al, and has been confirmed and extended by work in a number of laboratories in the last few years. Here we present an atomic model for structural changes involved in the vectorial, light-driven transport of protons by bacteriorhodopsin. A 'switch' mechanism ensures the vectorial nature of pumping. First, retinal unbends, triggered by loss of the Schiff base proton, and second, a protein conformational change occurs. This conformational change, which we have determined by electron crystallography at atomic (3.2 A in-plane and 3.6 A vertical) resolution, is largely localized to helices F and G, and provides an 'opening' of the protein to protons on the cytoplasmic side of the membrane.
PDB ID: 1FBKDownload
MMDB ID: 14206
PDB Deposition Date: 2000/7/15
Updated in MMDB: 2017/10
Experimental Method:
electron crystallography
Resolution: 3.2  Å
Source Organism:
Similar Structures:
Biological Unit for 1FBK: trimeric; determined by author and by software (PISA,PQS)
Molecular Components in 1FBK
Label Count Molecule
Proteins (3 molecules)
3
Bacteriorhodopsin(Gene symbol: VNG_RS05715)
Molecule annotation
Chemicals (3 molecules)
1
3
* Click molecule labels to explore molecular sequence information.

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