title: Salt bridge in the conserved His-Asp cluster in Gloeobacter rhodopsin contributes to trimer formation.
abstract: 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-β-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.
authors: Faculty of Advanced Life Science, Hokkaido University, Sapporo 060-0810, Japan.
authors: Takashi
authors: T
authors: Tsukamoto
authors: Takashi
authors: T
authors: Kikukawa
authors: Takuro
authors: T
authors: Kurata
authors: Kwang-Hwan
authors: KH
authors: Jung
authors: Naoki
authors: N
authors: Kamo
authors: Makoto
authors: M
authors: Demura
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D001224:Aspartic Acid / Q000737:chemistry* / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D001436:Bacteriorhodopsins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D002850:Chromatography, Gel; D002942:Circular Dichroism; D017124:Conserved Sequence; D000458:Cyanobacteria / Q000378:metabolism*; D003902:Detergents / Q000737:chemistry; D005960:Glucosides / Q000737:chemistry; D006639:Histidine / Q000737:chemistry* / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D008958:Models, Molecular; D050505:Mutant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D020836:Protein Structure, Quaternary; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D012545:Schiff Bases
chemical_list: D001426:Bacterial Proteins; D003902:Detergents; D005960:Glucosides; D050505:Mutant Proteins; D011994:Recombinant Proteins; D012545:Schiff Bases; D001224:Aspartic Acid; D006639:Histidine; D001436:Bacteriorhodopsins; C017827:bacterio-opsin; C040358:dodecyl maltoside