title: Structural differences between wild-type and fish eye disease mutant of lecithin:cholesterol acyltransferase.
abstract: Fluorescence spectroscopy has been used to investigate the conformational changes that occur upon binding of wild type (WT) and mutant (Thr123Ile) lecithin:cholesterol acyltransferase (LCAT) to the potential substrates (dioleoyl-phosphatidyl choline [DOPC] and high density lipoprotein [HDL]). For a detailed analysis of structural differences between WT and mutant LCAT, we performed decompositional analysis of a set of tryptophan fluorescence spectra, measured at increasing concentrations of external quenchers (acrylamide and KI). The data obtained show that Thr123Ile mutation in LCAT leads to a conformation that is likely to be more rigid (less mobile/flexible) than that of the WT protein with a redistribution of charged residues around exposed tryptophan fluorophores. We propose that the redistribution of charged residues in mutant LCAT may be a major factor responsible for the dramatically reduced activity of the enzyme with HDL and reconstituted high density lipoprotein (rHDL).
authors.affiliation: Department of Physics, University of Rhode Island, Kingston, Rhode Island 02881, USA. reshetnyak@mail.uri.edu
authors.forename: Yana
authors.initials: Y
authors.lastname: Reshetnyak
authors.forename: Kissaou T
authors.initials: KT
authors.lastname: Tchedre
authors.forename: Maya P
authors.initials: MP
authors.lastname: Nair
authors.forename: P Haydn
authors.initials: PH
authors.lastname: Pritchard
authors.forename: Andras G
authors.initials: AG
authors.lastname: Lacko
mesh_terms: D019943:Amino Acid Substitution; D008076:Cholesterol, HDL / Q000378:metabolism; D006801:Humans; D007863:Lecithin Cholesterol Acyltransferase Deficiency / Q000235:genetics*; D007862:Phosphatidylcholine-Sterol O-Acyltransferase / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D013050:Spectrometry, Fluorescence; D014364:Tryptophan / Q000737:chemistry / Q000235:genetics
chemical_list: D008076:Cholesterol, HDL; D014364:Tryptophan; D007862:Phosphatidylcholine-Sterol O-Acyltransferase