5AX1

Crystal Structure of the Cell-Free Synthesized Membrane Protein, Acetabularia Rhodopsin I, at 1.80 angstrom

Replaces:  3WTA

Summary for 5AX1

• Entry DOI: 10.2210/pdb5ax1/pdb
• Related: 5AWZ 5AX0
• Descriptor: Rhodopsin I, RETINAL, (2S)-2,3-dihydroxypropyl (9Z)-octadec-9-enoate, ... (8 entities in total)
• Functional Keywords: proton transport, membrane protein, retinal, water cluster, green algae, phototaxis, cell-free synthesis, microbial-type rhodopsin, light-driven proton pump
• Biological source: Acetabularia acetabulum (Mermaid's wine glass)
• Total number of polymer chains: 1
• Total formula weight: 28523.84

Authors

Furuse, M.,Hosaka, T.,Kimura-Someya, T.,Yokoyama, S.,Shirouzu, M. (deposition date: 2015-07-10, release date: 2015-08-26, Last modification date: 2024-11-06)

Primary citation

Furuse, M.,Tamogami, J.,Hosaka, T.,Kikukawa, T.,Shinya, N.,Hato, M.,Ohsawa, N.,Kim, S.Y.,Jung, K.H.,Demura, M.,Miyauchi, S.,Kamo, N.,Shimono, K.,Kimura-Someya, T.,Yokoyama, S.,Shirouzu, M.
Structural basis for the slow photocycle and late proton release in Acetabularia rhodopsin I from the marine plant Acetabularia acetabulum
Acta Crystallogr.,Sect.D, 71:2203-2216, 2015

PubMed Abstract: Although many crystal structures of microbial rhodopsins have been solved, those with sufficient resolution to identify the functional water molecules are very limited. In this study, the Acetabularia rhodopsin I (ARI) protein derived from the marine alga A. acetabulum was synthesized on a large scale by the Escherichia coli cell-free membrane-protein production method, and crystal structures of ARI were determined at the second highest (1.52-1.80 Å) resolution for a microbial rhodopsin, following bacteriorhodopsin (BR). Examinations of the photochemical properties of ARI revealed that the photocycle of ARI is slower than that of BR and that its proton-transfer reactions are different from those of BR. In the present structures, a large cavity containing numerous water molecules exists on the extracellular side of ARI, explaining the relatively low pKa of Glu206(ARI), which cannot function as an initial proton-releasing residue at any pH. An interhelical hydrogen bond exists between Leu97(ARI) and Tyr221(ARI) on the cytoplasmic side, which facilitates the slow photocycle and regulates the pKa of Asp100(ARI), a potential proton donor to the Schiff base, in the dark state.

PubMed: 26527138
DOI: 10.1107/S1399004715015722

Experimental method

X-RAY DIFFRACTION (1.803 Å)