Publications

• Marine Proteobacteria metabolize glycolate via the beta-hydroxyaspartate cycle.

  Schada von Borzyskowski L., Severi F., Krueger K., Hermann L., Gilardet A., Sippel F., Pommerenke B., Claus P., Cortina N.S., Glatter T., Zauner S., Zarzycki J., Fuchs B.M., Bremer E., Maier U.G., Amann R.I., Erb T.J.

  One of the most abundant sources of organic carbon in the ocean is glycolate, the secretion of which by marine phytoplankton results in an estimated annual flux of one petagram of glycolate in marine environments¹. Although it is generally accepted that glycolate is oxidized to glyoxyla ... >> More

  One of the most abundant sources of organic carbon in the ocean is glycolate, the secretion of which by marine phytoplankton results in an estimated annual flux of one petagram of glycolate in marine environments¹. Although it is generally accepted that glycolate is oxidized to glyoxylate by marine bacteria^2-4, the further fate of this C₂ metabolite is not well understood. Here we show that ubiquitous marine Proteobacteria are able to assimilate glyoxylate via the β-hydroxyaspartate cycle (BHAC) that was originally proposed 56 years ago⁵. We elucidate the biochemistry of the BHAC and describe the structure of its key enzymes, including a previously unknown primary imine reductase. Overall, the BHAC enables the direct production of oxaloacetate from glyoxylate through only four enzymatic steps, representing-to our knowledge-the most efficient glyoxylate assimilation route described to date. Analysis of marine metagenomes shows that the BHAC is globally distributed and on average 20-fold more abundant than the glycerate pathway, the only other known pathway for net glyoxylate assimilation. In a field study of a phytoplankton bloom, we show that glycolate is present in high nanomolar concentrations and taken up by prokaryotes at rates that allow a full turnover of the glycolate pool within one week. During the bloom, genes that encode BHAC key enzymes are present in up to 1.5% of the bacterial community and actively transcribed, supporting the role of the BHAC in glycolate assimilation and suggesting a previously undescribed trophic interaction between autotrophic phytoplankton and heterotrophic bacterioplankton. << Less

  Nature 575:500-504(2019) [PubMed] [EuropePMC]

  This publication is cited by 4 other entries.

• A novel enzyme, D-3-hydroxyaspartate aldolase from Paracoccus denitrificans IFO 13301: purification, characterization, and gene cloning.

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

  A novel enzyme, D-3-hydroxyaspartate aldolase (D-HAA), catalyzing the conversion of D-3-hydroxyaspartate to glyoxylate plus glycine, was purified to homogeneity from Paracoccus denitrificans IFO 13301. D-HAA is strictly D-specific as to the alpha-position, whereas the enzyme does not distinguish b ... >> More

  A novel enzyme, D-3-hydroxyaspartate aldolase (D-HAA), catalyzing the conversion of D-3-hydroxyaspartate to glyoxylate plus glycine, was purified to homogeneity from Paracoccus denitrificans IFO 13301. D-HAA is strictly D-specific as to the alpha-position, whereas the enzyme does not distinguish between threo and erythro forms at the beta-position. In addition to D-3-hydroxyaspartate, the enzyme also acts on d-threonine, D-3-3,4-dihydroxyphenylserine, D-3-3,4-methylenedioxyphenylserine, and D-3-phenylserine. The D-HAA gene was cloned and sequenced. The gene contains an open reading frame consisting of 1,161 nucleotides corresponding to 387 amino acid residues. The predicted amino acid sequence displayed 35% and 22% identity with that of the D-threonine aldolase of Arthrobacter sp. DK-38 and Alcaligenes xylosoxidan IFO 12669, respectively. This is the first paper reporting both a purified enzyme with D-3-hydroxyaspartate aldolase activity and also its gene cloning. << Less

  Appl. Microbiol. Biotechnol. 62:53-60(2003) [PubMed] [EuropePMC]

  This publication is cited by 1 other entry.