Salt bridge in the conserved His-Asp cluster in Gloeobacter rhodopsin contributes to trimer formation

초록

Gloeobacter rhodopsin (GR) is a eubacterial proton pump having a highly conserved histidine near the retinal Schiff base counter-ion, aspartate. Various interactions between His and Asp of the eubacterial proton pump have been reported. Here, we showed the pH-dependent trimer/monomer transition of GR in the presence of dodecyl-beta-D-maltoside by size-exclusion chromatography. The pH dependence was closely related to the protonation state of the counter-ion, Asp121. For the H87M mutant, pH dependence disappeared and a monomer became dominant. We concluded that the formation or breaking of the salt bridge between His87 and Asp121 inside the protein changes the quaternary structure. Structured summary of protein interactions: Rhodopsin and Rhodopsin bind by molecular sieving (View interaction) Rhodopsin and Rhodopsin bind by molecular sieving (View interaction: 1, 2) (C) 2013 Federation of European Biochemical Societies. Published by Elsevier B. V. All rights reserved.

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