title: Effects of mutations of Lys41 and Asp102 of bacteriorhodopsin.
abstract: Bacteriorhodopsin (BR) is a retinal protein that functions as a light-driven proton pump. In this study, six novel mutants including K41E and D102K, were obtained to verify or rule out the possibility that residues Lys41 and Asp102 are determinants of the time order of proton release and uptake, because we found that the order was reversed in another retinal protein archaerhodopsin 4 (AR4), which had different 41th and 102th residues. Our results rule out that possibility and confirm that the pK(a) of the proton release complex (PRC) determines the time order. Nevertheless, mutations, especially D102K, were found to affect the kinetics of proton uptake substantially and the pK(a) of Asp96. Compared to the wild-type BR (BR-WT), the decay of the M intermediate and proton uptake in the photocycle was slowed about 3-fold in D102K. Hence those residues might be involved in proton uptake and delivery to the internal proton donor.
authors: Key Laboratory of Molecular Engineering of Polymers of the Ministry of Education, Department of Macromolecular Science, Laboratory of Advanced Materials, Fudan University, Shanghai, China.
authors: Yingchun
authors: Y
authors: Zhao
authors: Yazhuo
authors: Y
authors: Wang
authors: Dewang
authors: D
authors: Ma
authors: Jia
authors: J
authors: Wu
authors: Weida
authors: W
authors: Huang
authors: Jiandong
authors: J
authors: Ding
mesh_terms: D000595:Amino Acid Sequence; D001216:Asparagine / Q000235:genetics; D001436:Bacteriorhodopsins / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D019617:Halobacterium salinarum / Q000737:chemistry / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008027:Light; D008239:Lysine / Q000235:genetics; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed / Q000379:methods*; D009154:Mutation / Q000235:genetics*; D017494:Proton Pumps / Q000737:chemistry / Q000235:genetics*; D012172:Retinaldehyde / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: D017494:Proton Pumps; D001436:Bacteriorhodopsins; D001216:Asparagine; D008239:Lysine; D012172:Retinaldehyde