title: Spectroscopic and photochemical analysis of proteorhodopsin variants from the surface of the Arctic Ocean.
abstract: Proteorhodopsin (PR), a retinal-containing seven transmembrane helix protein, functions as a light-driven proton pump. Using PCR, we isolated 18 PR variants originating from the surface of the Arctic Ocean. Their absorption maxima were between 517 and 546 nm at pH 7. One of the isolates turned out to be identical to GPR (green light-absorbing proteorhodopsin) from Monterey Bay. Interestingly, 10 isolates had replaced a tyrosine in the retinal-binding site (Tyr200 in GPR) with Asn. They showed a slower photocycle, more blue-shifted absorption maxima at pH 10, and relatively larger DeltaH and DeltaS of activation of the transition between the O intermediate and the ground state compared to GPR.
authors.affiliation: Department of Life Science and Interdisciplinary Program of Integrated Biotechnology, Sogang University, Shinsu-Dong 1, Mapo-Gu, Seoul 121-742, Republic of Korea.
authors.forename: Jae Yong
authors.initials: JY
authors.lastname: Jung
authors.forename: Ah Reum
authors.initials: AR
authors.lastname: Choi
authors.forename: Yoo Kyung
authors.initials: YK
authors.lastname: Lee
authors.forename: Hong Kum
authors.initials: HK
authors.lastname: Lee
authors.forename: Kwang-Hwan
authors.initials: KH
authors.lastname: Jung
mesh_terms: D000595:Amino Acid Sequence; D001110:Arctic Regions; D001665:Binding Sites; D008969:Molecular Sequence Data; D009792:Oceans and Seas; D010777:Photochemistry; D016133:Polymerase Chain Reaction; D017433:Protein Structure, Secondary; D012243:Rhodopsin / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification; D025604:Rhodopsins, Microbial; D012623:Seawater / Q000382:microbiology*; D013053:Spectrophotometry
chemical_list: D025604:Rhodopsins, Microbial; C413548:proteorhodopsin; D012243:Rhodopsin