title: Kinetic properties of chimeric class I aldehyde dehydrogenases for retinal isomers.
abstract: Retinal dehydrogenase type 1 (RALDH1) catalyzes the oxidation of all-trans and 9-cis retinal to the respective retinoic acids (RAs), whereas another member of the aldehyde dehydrogenase (ALDH) family, the phenobarbital-induced aldehyde dehydrogenase (PB-ALDH), is very poorly active. We have previously generated chimeras between these 2 enzymes that displayed selectivity for retinal isomers in crude bacterial extracts. Here we have characterized the kinetic properties of the corresponding purified recombinant proteins. The all-trans selective chimera RALDH-131 converted all-trans retinal to all-trans RA with 2.9-fold lower efficiency than the wild-type RALDH1 and had only residual activity with 9-cis retinal. The converse chimera PB-131 was specific for 9-cis retinal, with no residual activity for all-trans retinal. MgCl2 inhibited the activities of RALDH1 and PB-131, but not of RALDH-131, suggesting that amino acids 132-510 in RALDH are necessary for inhibition by MgCl2. These data demonstrate that the chimeric enzymes act as retinal isomer-selective ALDHs, and suggest that these enzymes may be useful to study the roles of cis RA isomers in embryogenesis and differentiation in vivo.
authors.affiliation: Laboratory of Nutrition and Cancer, Centre Hospitalier de l'Université de Montréal-Hotel Dieu, Université de Montréal, 3850 Saint Urbain St, Montréal, QC H2W 1T7, Canada.
authors.forename: Hélène
authors.initials: H
authors.lastname: Brodeur
authors.forename: Samuel
authors.initials: S
authors.lastname: Chagnon
authors.forename: Maxime
authors.initials: M
authors.lastname: Parisotto
authors.forename: Sylvie
authors.initials: S
authors.lastname: Mader
authors.forename: Pangala V
authors.initials: PV
authors.lastname: Bhat
mesh_terms: D000444:Aldehyde Dehydrogenase / Q000493:pharmacokinetics*; D000080924:Aldehyde Dehydrogenase 1 Family; D000077556:Alitretinoin; D000818:Animals; D007527:Isoenzymes / Q000493:pharmacokinetics*; D008274:Magnesium / Q000494:pharmacology; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000493:pharmacokinetics*; D050697:Retinal Dehydrogenase / Q000493:pharmacokinetics*; D014212:Tretinoin / Q000378:metabolism
chemical_list: D007527:Isoenzymes; D011993:Recombinant Fusion Proteins; D000077556:Alitretinoin; D014212:Tretinoin; D000080924:Aldehyde Dehydrogenase 1 Family; D000444:Aldehyde Dehydrogenase; C523119:Aldh1a1 protein, rat; D050697:Retinal Dehydrogenase; D008274:Magnesium