title: Allosteric modulation of the substrate specificity of acyl-CoA wax alcohol acyltransferase 2.
abstract: The esterification of alcohols with fatty acids is a universal mechanism to form inert storage forms of sterols, di- and triacylglycerols, and retinoids. In ocular tissues, formation of retinyl esters is an essential step in the enzymatic regeneration of the visual chromophore (11-cis-retinal). Acyl-CoA wax alcohol acyltransferase 2 (AWAT2), also known as multifunctionalO-acyltransferase (MFAT), is an integral membrane enzyme with a broad substrate specificity that has been shown to preferentially esterify 11-cis-retinol and thus contribute to formation of a readily available pool ofcisretinoids in the eye. However, the mechanism by which this promiscuous enzyme can gain substrate specificity is unknown. Here, we provide evidence for an allosteric modulation of the enzymatic activity by 11-cisretinoids. This regulation is independent from cellular retinaldehyde-binding protein (CRALBP), the majorcis-retinoid binding protein. This positive-feedback regulation leads to decreased esterification rates for 9-cis, 13-cis, or all-transretinols and thus enables preferential synthesis of 11-cis-retinyl esters. Finally, electron microscopy analyses of the purified enzyme indicate that this allosteric effect does not result from formation of functional oligomers. Altogether, these data provide the experimental basis for understanding regulation of AWAT2 substrate specificity.
authors.affiliation: Department of Pharmacology and School of Medicine, Case Western Reserve University, Cleveland, OH.
authors.forename: Jason M
authors.initials: JM
authors.lastname: Arne
authors.affiliation: Department of Pharmacology and School of Medicine, Case Western Reserve University, Cleveland, OH.
authors.forename: Made Airanthi K
authors.initials: MAK
authors.lastname: Widjaja-Adhi
authors.affiliation: Department of Pharmacology and School of Medicine, Case Western Reserve University, Cleveland, OH.
authors.forename: Taylor
authors.initials: T
authors.lastname: Hughes
authors.affiliation: Department of Pharmacology and School of Medicine, Case Western Reserve University, Cleveland, OH.
authors.forename: Kevin W
authors.initials: KW
authors.lastname: Huynh
authors.affiliation: Department of Pharmacology and School of Medicine, Case Western Reserve University, Cleveland, OH.
authors.forename: Josie A
authors.initials: JA
authors.lastname: Silvaroli
authors.affiliation: Department of Pharmacology and School of Medicine, Case Western Reserve University, Cleveland, OH; Laboratory of Hematology and Flow Cytometry, Department of Hematology, Military Institute of Medicine, Warsaw, Poland.
authors.forename: Sylwia
authors.initials: S
authors.lastname: Chelstowska
authors.affiliation: Department of Pharmacology and School of Medicine, Case Western Reserve University, Cleveland, OH; Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, OH; and.
authors.forename: Vera Y
authors.initials: VY
authors.lastname: Moiseenkova-Bell
authors.affiliation: Department of Pharmacology and School of Medicine, Case Western Reserve University, Cleveland, OH; Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, OH; and. Electronic address: mxg149@case.edu.
authors.forename: Marcin
authors.initials: M
authors.lastname: Golczak
mesh_terms: D000217:Acyltransferases / Q000737:chemistry / Q000378:metabolism*; D000438:Alcohols / Q000378:metabolism; D000494:Allosteric Regulation / Q000235:genetics; D000818:Animals; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism; D004951:Esterification; D004952:Esters / Q000378:metabolism; D005123:Eye / Q000254:growth & development / Q000378:metabolism* / Q000648:ultrastructure; D005227:Fatty Acids / Q000378:metabolism; D006801:Humans; D051379:Mice; D008854:Microscopy, Electron; D012176:Retinoids / Q000235:genetics / Q000378:metabolism*; D013379:Substrate Specificity; D014801:Vitamin A / Q000096:biosynthesis / Q000378:metabolism*
chemical_list: C020932:11-cis-retinal-binding protein; D000438:Alcohols; D002352:Carrier Proteins; D004952:Esters; D005227:Fatty Acids; D012176:Retinoids; D014801:Vitamin A; C000608943:AWAT2 protein, mouse; D000217:Acyltransferases
keywords: 11-cis-retinol; cone photoreceptor; multifunctional O-acyltransferase; visual cycle; vitamin A