4FPD

Deprotonation of D96 in bacteriorhodopsin opens the proton uptake pathway

Summary for 4FPD

• Entry DOI: 10.2210/pdb4fpd/pdb
• Related: 1FBK 1JV7 1KG8 1KG9 1KGB
• Descriptor: Bacteriorhodopsin, RETINAL, CHLORIDE ION, ... (5 entities in total)
• Functional Keywords: 7 helix, transmembrane, proton pump, ion transport, deprotonation, retinal binding, membrane, transport protein
• Biological source: Halobacterium sp. NRC-1
• Total number of polymer chains: 1
• Total formula weight: 33566.94

Authors

Wang, T.,Sessions, A.O.,Lunde, C.S.,Rouani, S.,Glaeser, R.M.,Facciotti, M.T.,Duan, Y. (deposition date: 2012-06-22, release date: 2013-02-27, Last modification date: 2024-10-16)

Primary citation

Wang, T.,Sessions, A.O.,Lunde, C.S.,Rouhani, S.,Glaeser, R.M.,Duan, Y.,Facciotti, M.T.
Deprotonation of d96 in bacteriorhodopsin opens the proton uptake pathway.
Structure, 21:290-297, 2013

PubMed Abstract: Despite extensive investigation, the precise mechanism controlling the opening of the cytoplasmic proton uptake pathway in bacteriorhodopsin (bR) has remained a mystery. From an analysis of the X-ray structure of the D96G/F171C/F219L triple mutant of bR and 60 independent molecular dynamics simulations of bR photointermediates, we report that the deprotonation of D96, a key residue in proton transfer reactions, serves two roles that occur sequentially. First, D96 donates a proton to the Schiff base. Subsequently, the deprotonation of D96 serves to "unlatch" the cytoplasmic side. The latching function of D96 appears to be remarkably robust, functioning to open hydration channels in all photointermediate structures. These results suggest that the protonation state of D96 may be the critical biophysical cue controlling the opening and closing of the cytoplasmic half-channel in bR. We suspect that this protonation-switch mechanism could also be utilized in other proton pumps to minimize backflow and reinforce directionality.

PubMed: 23394942
DOI: 10.1016/j.str.2012.12.018

Experimental method

X-RAY DIFFRACTION (2.65 Å)