title: Arg-72 of pharaonis phoborhodopsin (sensory rhodopsin II) is important for the maintenance of the protein structure in the solubilized states.
abstract: In bacteriorhodopsin (bR), Arg-82bR has been proven to be a very important residue for functional role of this light-driven proton pump. The arginine residue at this position is a super-conserved residue among archaeal rhodopsins. pharaonis phoborhodopsin (ppR; or called as "pharaonis sensory rhodopsin II") has its absorption maximum at 498 nm and acts as a sensor in the membrane of Natronobacterium pharaonis, mediating the negative phototaxis from the light of wavelength shorter than 520 nm. To investigate the role of the arginine residue (Arg-72ppR) of ppR corresponding to Arg-82bR, mutants whose Arg-72ppR was replaced by alanine (R72A), lysine (R72K), glutamine (R72Q) and serine (R72S) were prepared. These mutants were unstable in low concentrations of NaCl and lost their color gradually when the proteins were solubilized with 0.1% n-dodecyl-beta-D-maltoside. The order of instability was R72S > R72A > R72K > R72Q > the wild type. The rates of denaturation were reduced in a solution of high concentrations of monovalent anions.
authors.affiliation: Laboratory of Biophysical Chemistry, Graduate School of Pharmaceutical Sciences, Hokkaido University, Sapporo, Japan.
authors.forename: Yukako
authors.initials: Y
authors.lastname: Ikeura
authors.forename: Kazumi
authors.initials: K
authors.lastname: Shimono
authors.forename: Masayuki
authors.initials: M
authors.lastname: Iwamoto
authors.forename: Yuki
authors.initials: Y
authors.lastname: Sudo
authors.forename: Naoki
authors.initials: N
authors.lastname: Kamo
mesh_terms: D000838:Anions / Q000378:metabolism; D019843:Archaeal Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D001120:Arginine / Q000235:genetics / Q000378:metabolism*; D002338:Carotenoids / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D002712:Chlorides / Q000378:metabolism; D025602:Halorhodopsins; D009154:Mutation; D011487:Protein Conformation; D011489:Protein Denaturation; D025603:Sensory Rhodopsins; D020539:Sequence Analysis, Protein; D012965:Sodium Chloride / Q000737:chemistry; D012995:Solubility; D012996:Solutions; D013696:Temperature
chemical_list: D000838:Anions; D019843:Archaeal Proteins; D002712:Chlorides; D025602:Halorhodopsins; D025603:Sensory Rhodopsins; D012996:Solutions; C061508:sensory rhodopsin II protein, archaeal; D002338:Carotenoids; D012965:Sodium Chloride; D001120:Arginine