title: Structural determinants and modulation of substrate specificity in phenylalanine-tyrosine ammonia-lyases.
abstract: Aromatic amino acid ammonia-lyases catalyze the deamination of L-His, L-Phe, and L-Tyr, yielding ammonia plus aryl acids bearing an alpha,beta-unsaturated propenoic acid. We report crystallographic analyses of unliganded Rhodobacter sphaeroides tyrosine ammonia-lyase (RsTAL) and RsTAL bound to p-coumarate and caffeate. His 89 of RsTAL forms a hydrogen bond with the p-hydroxyl moieties of coumarate and caffeate. His 89 is conserved in TALs but replaced in phenylalanine ammonia-lyases (PALs) and histidine ammonia-lyases (HALs). Substitution of His 89 by Phe, a characteristic residue of PALs, yields a mutant with a switch in kinetic preference from L-Tyr to L-Phe. Structures of the H89F mutant in complex with the PAL product, cinnamate, or the PAL-specific inhibitor, 2-aminoindan-2-phosphonate (AIP), support the role of position 89 as a specificity determinant in the family of aromatic amino acid ammonia-lyases and aminomutases responsible for beta-amino acid biosynthesis.
authors.affiliation: Howard Hughes Medical Institute, Jack H. Skirball Center for Chemical Biology and Proteomics, The Salk Institute for Biological Studies, La Jolla, California 92037, USA.
authors.forename: Gordon V
authors.initials: GV
authors.lastname: Louie
authors.forename: Marianne E
authors.initials: ME
authors.lastname: Bowman
authors.forename: Michelle C
authors.initials: MC
authors.lastname: Moffitt
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Baiga
authors.forename: Bradley S
authors.initials: BS
authors.lastname: Moore
authors.forename: Joseph P
authors.initials: JP
authors.lastname: Noel
mesh_terms: D000595:Amino Acid Sequence; D000642:Ammonia-Lyases / Q000737:chemistry / Q000378:metabolism; D001665:Binding Sites; D002109:Caffeic Acids / Q000737:chemistry; D003373:Coumaric Acids / Q000737:chemistry; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D008969:Molecular Sequence Data; D015394:Molecular Structure; D010649:Phenylalanine / Q000737:chemistry / Q000378:metabolism; D012242:Rhodobacter sphaeroides / Q000201:enzymology; D016415:Sequence Alignment; D013379:Substrate Specificity
chemical_list: D002109:Caffeic Acids; D003373:Coumaric Acids; D010649:Phenylalanine; D000642:Ammonia-Lyases; C023208:L-tyrosine ammonia-lyase; C040048:caffeic acid