title: Amino acid residues responsible for the meta-III decay rates in rod and cone visual pigments.
abstract: Vertebrate retinas have two types of photoreceptor cells, rods and cones, which contain visual pigments with different molecular properties. These pigments diverged from a common ancestor, and their difference in molecular properties originates from the difference in their amino acid residues. We previously reported that the difference in decay times of G protein-activating meta-II intermediates between the chicken rhodopsin and green-sensitive cone (chicken green) pigments is about 50 times. This difference only originates from the differences of two residues at positions 122 and 189 (Kuwayama, S., Imai, H., Hirano, T., Terakita, A., and Shichida, Y. (2002) Biochemistry 41, 15245-15252). Here we show that the meta-III intermediates exhibit about 700 times difference in decay times between the two pigments, and the faster decay in chicken green can be converted to the slower decay in rhodopsin by replacing the residues in chicken green with the corresponding rhodopsin residues. However, the inverse directional conversion did not occur when the two residues in rhodopsin were replaced by those of chicken green. Analysis using chimerical mutants derived from these pigments has demonstrated that amino acid residues responsible for the slow rhodopsin meta-III decay are situated at several positions throughout the C-terminal half of rhodopsin. Considering that rhodopsins evolved from cone pigments, it has been suggested that the molecular properties of rhodopsin have been optimized by mutations at several positions, and the chicken green mutants at two positions could be rhodopsin-like pigments transiently produced in the course of molecular evolution.
authors.affiliation: Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto 606-8502, and CREST, Japan Science and Technology Agency, Kyoto, Japan.
authors.forename: Shigeki
authors.initials: S
authors.lastname: Kuwayama
authors.forename: Hiroo
authors.initials: H
authors.lastname: Imai
authors.forename: Takefumi
authors.initials: T
authors.lastname: Morizumi
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Shichida
mesh_terms: D000595:Amino Acid Sequence / Q000235:genetics / Q000528:radiation effects; D019943:Amino Acid Substitution / Q000235:genetics; D000596:Amino Acids / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D030161:Avian Proteins; D002417:Cattle; D002460:Cell Line; D002645:Chickens; D019143:Evolution, Molecular; D005136:Eye Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism* / Q000528:radiation effects; D005960:Glucosides / Q000737:chemistry; D006801:Humans; D008027:Light; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012168:Retinal Pigments / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism* / Q000528:radiation effects; D012172:Retinaldehyde / Q000737:chemistry; D012243:Rhodopsin / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism* / Q000528:radiation effects; D017299:Rod Opsins / Q000378:metabolism; D013056:Spectrophotometry, Ultraviolet; D013997:Time Factors
chemical_list: D000596:Amino Acids; D030161:Avian Proteins; D005136:Eye Proteins; D005960:Glucosides; D011993:Recombinant Fusion Proteins; D012168:Retinal Pigments; D017299:Rod Opsins; C088721:RHO rhodopsin protein, chicken; C040358:dodecyl maltoside; D012243:Rhodopsin; D012172:Retinaldehyde