4QRY

the ground state and the N intermediate of pharaonis halorhodopsin in complex with bromide ion

Summary for 4QRY

• Entry DOI: 10.2210/pdb4qry/pdb
• Related: 3a7k 3abw 3qbg 3qbk 3vvk
• Descriptor: Halorhodopsin, RETINAL, BROMIDE ION, ... (6 entities in total)
• Functional Keywords: 7 transmembrane helices, light-driven chloride ion pump, retinal bacterioruberin, membrane, membrane protein
• Biological source: Natronomonas pharaonis
• Total number of polymer chains: 6
• Total formula weight: 193966.96

Authors

Kouyama, T.,Kawaguchi, H. (deposition date: 2014-07-02, release date: 2015-06-17, Last modification date: 2024-11-20)

Primary citation

Kouyama, T.,Kawaguchi, H.,Nakanishi, T.,Kubo, H.,Murakami, M.
Crystal Structures of the L1, L2, N, and O States of pharaonis Halorhodopsin
Biophys.J., 108:2680-2690, 2015

PubMed Abstract: Halorhodopsin from Natronomonas pharaonis (pHR) functions as a light-driven halide ion pump. In the presence of halide ions, the photochemical reaction of pHR is described by the scheme: K→ L1 → L2 → N → O → pHR' → pHR. Here, we report light-induced structural changes of the pHR-bromide complex observed in the C2 crystal. In the L1-to-L2 transition, the bromide ion that initially exists in the extracellular vicinity of retinal moves across the retinal Schiff base. Upon the formation of the N state with a bromide ion bound to the cytoplasmic vicinity of the retinal Schiff base, the cytoplasmic half of helix F moves outward to create a water channel in the cytoplasmic interhelical space, whereas the extracellular half of helix C moves inward. During the transition from N to an N-like reaction state with retinal assuming the 13-cis/15-syn configuration, the translocated bromide ion is released into the cytoplasmic medium. Subsequently, helix F relaxes into its original conformation, generating the O state. Anion uptake from the extracellular side occurs when helix C relaxes into its original conformation. These structural data provide insight into the structural basis of unidirectional anion transport.

PubMed: 26039169
DOI: 10.1016/j.bpj.2015.04.027

Experimental method

X-RAY DIFFRACTION (2.2 Å)