Publications

• Preliminary data on the structure and embryogenesis of the parietal eye in Chalcides ocellatus (Lep. Scin.).

  Lipari E.F., Lipari D.

  Acta Embryol Morphol Exp (Halocynthia Assoc) 3:189-199(1982) [PubMed] [EuropePMC]

• Discovery of a substrate selectivity switch in tyrosine ammonia-lyase, a member of the aromatic amino acid lyase family.

  Watts K.T., Mijts B.N., Lee P.C., Manning A.J., Schmidt-Dannert C.

  Tyrosine ammonia-lyase (TAL) is a recently described member of the aromatic amino acid lyase family, which also includes phenylalanine (PAL) and histidine ammonia-lyases (HAL). TAL is highly selective for L-tyrosine, and synthesizes 4-coumaric acid as a protein cofactor or antibiotic precursor in ... >> More

  Tyrosine ammonia-lyase (TAL) is a recently described member of the aromatic amino acid lyase family, which also includes phenylalanine (PAL) and histidine ammonia-lyases (HAL). TAL is highly selective for L-tyrosine, and synthesizes 4-coumaric acid as a protein cofactor or antibiotic precursor in microorganisms. In this report, we identify a single active site residue important for substrate selection in this enzyme family. Replacing the active site residue His89 with Phe in TAL completely switched its substrate selectivity from tyrosine to phenylalanine, thereby converting it into a highly active PAL. When a corresponding mutation was made in PAL, the enzyme lost PAL activity and gained TAL activity. The discovered substrate selectivity switch is a rare example of a complete alteration of substrate specificity by a single point mutation. We also show that the identity of the amino acid at the switch position can serve as a guide to predict substrate specificities of annotated aromatic amino acid lyases in genome sequences. << Less

  Chem Biol 13:1317-1326(2006) [PubMed] [EuropePMC]

• Maize phenylalanine ammonia-lyase has tyrosine ammonia-lyase activity.

  Roesler J., Krekel F., Amrhein N., Schmid J.

  A full-length cDNA encoding phenylalanine ammonia-lyase (PAL) from Zea mays L. was isolated and the coding region was expressed in Escherichia coli as a C-terminal fusion to glutathione S-transferase. After purification by glutathione-Sepharose chromatography, the glutathione S-transferase moiety ... >> More

  A full-length cDNA encoding phenylalanine ammonia-lyase (PAL) from Zea mays L. was isolated and the coding region was expressed in Escherichia coli as a C-terminal fusion to glutathione S-transferase. After purification by glutathione-Sepharose chromatography, the glutathione S-transferase moiety was cleaved off and the resulting PAL enzyme analyzed. In contrast to PAL from dicots, this maize PAL isozyme catalyzed the deamination of both L-phenylalanine (PAL activity) and L-tyrosine (tyrosine ammonia-lyase activity). These results provide unequivocal proof that PAL and tyrosine ammonia-lyase activities reside in the same polypeptide. In spite of large differences in the Michaelis constant and turnover number of the two activities, their catalytic efficiencies are very similar. Also, both activities have the same pH and temperature optima. These results imply that maize can produce p-coumaric acid from both phenylalanine and tyrosine. << Less

  Plant Physiol. 113:175-179(1997) [PubMed] [EuropePMC]

• Probing the active site of MIO-dependent aminomutases, key catalysts in the biosynthesis of beta-amino acids incorporated in secondary metabolites.

  Cooke H.A., Bruner S.D.

  The tyrosine aminomutase SgTAM produces (S)-ss-tyrosine from L-tyrosine in the biosynthesis of the enediyne antitumor antibiotic C-1027. This conversion is promoted by the methylideneimidazole-5-one (MIO) prosthetic group. MIO was first identified in the homologous family of ammonia lyases, which ... >> More

  The tyrosine aminomutase SgTAM produces (S)-ss-tyrosine from L-tyrosine in the biosynthesis of the enediyne antitumor antibiotic C-1027. This conversion is promoted by the methylideneimidazole-5-one (MIO) prosthetic group. MIO was first identified in the homologous family of ammonia lyases, which deaminate aromatic amino acids to form alpha,ss-unsaturated carboxylates. Studies of substrate specificity have been described for lyases but there have been limited reports in altering the substrate specificity of aminomutases. Furthermore, it remains unclear as to what structural properties are responsible for catalyzing the presumed readdition of the amino group into the alpha,ss-unsaturated intermediates to form ss-amino acids. Attempts to elucidate specificity and mechanistic determinants of SgTAM have also proved to be difficult as it is recalcitrant to perturbations to the active site via mutagenesis. An X-ray cocrystal structure of the SgTAM mutant of the catalytic base with L-tyrosine verified important substrate binding residues as well as the enzymatic base. Further mutagenesis revealed that removal of these crucial interactions renders the enzyme inactive. Proposed structural determinants for mutase activity probed via mutagenesis, time-point assays and X-ray crystallography revealed a complicated role for these residues in maintaining key quaternary structure properties that aid in catalysis. << Less

  Biopolymers 93:802-810(2010) [PubMed] [EuropePMC]

  This publication is cited by 1 other entry.

• A gut-derived metabolite alters brain activity and anxiety behaviour in mice.

  Needham B.D., Funabashi M., Adame M.D., Wang Z., Boktor J.C., Haney J., Wu W.L., Rabut C., Ladinsky M.S., Hwang S.J., Guo Y., Zhu Q., Griffiths J.A., Knight R., Bjorkman P.J., Shapiro M.G., Geschwind D.H., Holschneider D.P., Fischbach M.A., Mazmanian S.K.

  Integration of sensory and molecular inputs from the environment shapes animal behaviour. A major site of exposure to environmental molecules is the gastrointestinal tract, in which dietary components are chemically transformed by the microbiota¹ and gut-derived metabolites are dissemin ... >> More

  Integration of sensory and molecular inputs from the environment shapes animal behaviour. A major site of exposure to environmental molecules is the gastrointestinal tract, in which dietary components are chemically transformed by the microbiota¹ and gut-derived metabolites are disseminated to all organs, including the brain². In mice, the gut microbiota impacts behaviour³, modulates neurotransmitter production in the gut and brain^4,5, and influences brain development and myelination patterns^6,7. The mechanisms that mediate the gut-brain interactions remain poorly defined, although they broadly involve humoral or neuronal connections. We previously reported that the levels of the microbial metabolite 4-ethylphenyl sulfate (4EPS) were increased in a mouse model of atypical neurodevelopment⁸. Here we identified biosynthetic genes from the gut microbiome that mediate the conversion of dietary tyrosine to 4-ethylphenol (4EP), and bioengineered gut bacteria to selectively produce 4EPS in mice. 4EPS entered the brain and was associated with changes in region-specific activity and functional connectivity. Gene expression signatures revealed altered oligodendrocyte function in the brain, and 4EPS impaired oligodendrocyte maturation in mice and decreased oligodendrocyte-neuron interactions in ex vivo brain cultures. Mice colonized with 4EP-producing bacteria exhibited reduced myelination of neuronal axons. Altered myelination dynamics in the brain have been associated with behavioural outcomes^7,9-14. Accordingly, we observed that mice exposed to 4EPS displayed anxiety-like behaviours, and pharmacological treatments that promote oligodendrocyte differentiation prevented the behavioural effects of 4EPS. These findings reveal that a gut-derived molecule influences complex behaviours in mice through effects on oligodendrocyte function and myelin patterning in the brain. << Less

  Nature 602:647-653(2022) [PubMed] [EuropePMC]

  This publication is cited by 3 other entries.

• Yeast phenylalanine ammonia-lyase. Purification, properties, and the identification of catalytically essential dehydroalanine.

  Hodgins D.S.

  J. Biol. Chem. 246:2977-2985(1971) [PubMed] [EuropePMC]

• Structural determinants and modulation of substrate specificity in phenylalanine-tyrosine ammonia-lyases.

  Louie G.V., Bowman M.E., Moffitt M.C., Baiga T.J., Moore B.S., Noel J.P.

  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-c ... >> More

  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. << Less

  Chem. Biol. 13:1327-1338(2006) [PubMed] [EuropePMC]

  This publication is cited by 1 other entry.

• Discovery of additional members of the tyrosine aminomutase enzyme family and the mutational analysis of CmdF.

  Krug D., Muller R.

  The tyrosine aminomutase (TAM) CmdF converts L-Tyr preferentially to (R)-beta-Tyr--a biosynthetic building block subsequently incorporated into the highly cytotoxic chondramides by the myxobacterium Chondromyces crocatus. Together with the similar enzymes SgcC4 from Streptomyces globisporus and Md ... >> More

  The tyrosine aminomutase (TAM) CmdF converts L-Tyr preferentially to (R)-beta-Tyr--a biosynthetic building block subsequently incorporated into the highly cytotoxic chondramides by the myxobacterium Chondromyces crocatus. Together with the similar enzymes SgcC4 from Streptomyces globisporus and MdpC4 from Actinomadura madurae, which preferentially produce (S)-beta-Tyr, CmdF belongs to a novel 2,3-aminomutase enzyme family closely related to the aromatic amino acid ammonia lyase. Although considerable insight into the underlying catalytic mechanism has been provided recently by structural and mechanistic studies, the key determinants of product specificity and stereochemical preference of TAM enzymes remain to be elucidated in detail. We report herein the discovery and heterologous expression of additional TAMs from prokaryotic sources. These studies reveal a high degree of evolutionary diversification within this expanding enzyme family. Attempts to genetically engineer CmdF to exhibit ammonia lyase-type activity by the exchange of conserved sequence motifs were largely unsuccessful. However, the variation of a semiconserved glutamic acid residue was found to impact stereoselectivity. Replacement of this residue by lysine significantly increased the enantiomeric excess of (R)-beta-Tyr from 69 to 97 % ee, while substitution with methionine promoted racemization. These results suggest that it should be possible to elucidate a mechanism for control of stereoselectivity in the TAM family by the application of directed evolution to CmdF. Furthermore, our findings indicate the potential to fine-tune the catalytic properties of TAMs for their use as biocatalysts or in engineered biosynthetic pathways. << Less

  ChemBioChem 10:741-750(2009) [PubMed] [EuropePMC]

  This publication is cited by 1 other entry.