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Identification of conserved histidines and glutamic acid as key residues for isomerohydrolase activity of RPE65, an enzyme of the visual cycle in the retinal pigment epithelium
Author(s) -
Takahashi Yusuke,
Moiseyev Gennadiy,
Chen Ying,
Ma Jian-xing
Publication year - 2005
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/j.febslet.2005.09.002
Subject(s) - rpe65 , cis trans isomerases , retinal pigment epithelium , biochemistry , visual phototransduction , histidine , alanine , glutamic acid , retinal , chemistry , enzyme , pigment , glutamine , biology , amino acid , isomerase , peptidylprolyl isomerase , organic chemistry
We have recently reported that RPE65 from the retinal pigment epithelium is the isomerohydrolase, a critical enzyme in the visual cycle for regeneration of 11‐ cis retinal, the chromophore for visual pigments. Here, we demonstrated that mutation of any one of the absolutely conserved four histidine and one glutamic acid residues to alanine in RPE65 abolished its isomerohydrolase activity. Substitution of the conserved glutamic acid with glutamine also resulted in loss of the activity. Moreover, these mutations significantly reduced protein stability of RPE65. These results indicate that these conserved residues are essential for the isomerohydrolase activity of RPE65 and its stability.