Publications

• Gene cloning, biochemical characterization and physiological role of a thermostable low-specificity L-threonine aldolase from Escherichia coli.

  Liu J.-Q., Dairi T., Itoh N., Kataoka M., Shimizu S., Yamada H.

  The ltaE gene encoding for a thermostable low-specificity L-threonine aldolase, which catalyzes the cleavage of L-threonine/L-allo-threonine to glycine and acetaldehyde, was cloned from Escherichia coli GS245 by the polymerase chain reaction. Construction and expression of the plasmid pLTAE, which ... >> More

  The ltaE gene encoding for a thermostable low-specificity L-threonine aldolase, which catalyzes the cleavage of L-threonine/L-allo-threonine to glycine and acetaldehyde, was cloned from Escherichia coli GS245 by the polymerase chain reaction. Construction and expression of the plasmid pLTAE, which contained the ltaE gene under the control of the lac promoter, resulted in a 227-fold increase in the specific activity above the level detected in E. coli cells containing the control vector. The enzyme is thermostable: it retained its full activity upon heating at 60 degrees C for 1 h. The enzyme was thus feasibly purified to homogeneity by heat treatment and butyl-Toyopearl column chromatography, and characterized. To reveal the physiological role of the enzyme, gene disruption was performed. Knockout of the ltaE gene of wild-type E. coli did not effect the cellular growth rate, while disruption of the ltaE gene of E. coli GS245, whose serine hydroxymethyltransferase gene was knocked out, caused a significant decrease in the cellular growth rate, suggesting that the threonine aldolase is not a major source of cellular glycine in wild-type E. coli but catalyzes an alternative pathway for cellular glycine when serine hydroxymethyltransferase is inert. << Less

  Eur. J. Biochem. 255:220-226(1998) [PubMed] [EuropePMC]

  This publication is cited by 1 other entry.

• The GLY1 gene of Saccharomyces cerevisiae encodes a low-specific L-threonine aldolase that catalyzes cleavage of L-allo-threonine and L-threonine to glycine -- expression of the gene in Escherichia coli and purification and characterization of the enzyme.

  Liu J.-Q., Nagata S., Dairi T., Misono H., Shimizu S., Yamada H.

  The GLY1 gene of Saccharomyces cerevisiae is required for the biosynthesis of glycine for cell growth [McNeil, J. B., McIntosh, E. V., Taylor, B. V., Zhang, F-R., Tang, S. & Bognar, A. L. (1994) J. Biol. Chem. 269, 9155-9165], but its gene product has not been identified. We have found that the GL ... >> More

  The GLY1 gene of Saccharomyces cerevisiae is required for the biosynthesis of glycine for cell growth [McNeil, J. B., McIntosh, E. V., Taylor, B. V., Zhang, F-R., Tang, S. & Bognar, A. L. (1994) J. Biol. Chem. 269, 9155-9165], but its gene product has not been identified. We have found that the GLY1 protein is similar in primary structure to L-allo-threonine aldolase of Aeromonas jandiae DK-39, which stereospecifically catalyzes the interconversion of L-allo-threonine and glycine. The GLY1 gene was amplified by PCR, with a designed ribosome-binding site, cloned into pUC118, and expressed in Escherichia coli cells. The enzyme was purified to homogeneity, as judged by polyacrylamide gel electrophoresis. The enzyme has a molecular mass of about 170 kDa and consists of four subunits identical in molecular mass. The enzyme contains 2 mol pyridoxal 5'-phosphate/4 mol of subunit as a cofactor, and its absorption spectrum exhibits maxima at 280 nm and 420 nm. The enzyme catalyzes the cleavage of not only L-allo-threonine to glycine but also L-threonine. We have termed the enzyme a low-specific L-threonine aldolase to distinguish it from L-allo-threonine aldolase. << Less

  Eur. J. Biochem. 245:289-293(1997) [PubMed] [EuropePMC]

  This publication is cited by 1 other entry.

• One substrate many enzymes virtual screening uncovers missing genes of carnitine biosynthesis in human and mouse.

  Malatesta M., Fornasier E., Di Salvo M.L., Tramonti A., Zangelmi E., Peracchi A., Secchi A., Polverini E., Giachin G., Battistutta R., Contestabile R., Percudani R.

  The increasing availability of experimental and computational protein structures entices their use for function prediction. Here we develop an automated procedure to identify enzymes involved in metabolic reactions by assessing substrate conformations docked to a library of protein structures. By ... >> More

  The increasing availability of experimental and computational protein structures entices their use for function prediction. Here we develop an automated procedure to identify enzymes involved in metabolic reactions by assessing substrate conformations docked to a library of protein structures. By screening AlphaFold-modeled vitamin B6-dependent enzymes, we find that a metric based on catalytically favorable conformations at the enzyme active site performs best (AUROC Score=0.84) in identifying genes associated with known reactions. Applying this procedure, we identify the mammalian gene encoding hydroxytrimethyllysine aldolase (HTMLA), the second enzyme of carnitine biosynthesis. Upon experimental validation, we find that the top-ranked candidates, serine hydroxymethyl transferase (SHMT) 1 and 2, catalyze the HTMLA reaction. However, a mouse protein absent in humans (threonine aldolase; Tha1) catalyzes the reaction more efficiently. Tha1 did not rank highest based on the AlphaFold model, but its rank improved to second place using the experimental crystal structure we determined at 2.26 Å resolution. Our findings suggest that humans have lost a gene involved in carnitine biosynthesis, with HTMLA activity of SHMT partially compensating for its function. << Less

  Nat Commun 15:3199-3199(2024) [PubMed] [EuropePMC]

  This publication is cited by 2 other entries.