L-tyrosine is the precursor of PQQ biosynthesis in Hyphomicrobium X.
A method was developed to study amino acids as possible precursors of PQQ biosynthesis. Cultures of Hyphomicrobium X, growing on [13C]methanol, were supplemented with unlabelled amino acids. Uptake and participation in metabolism were determined via gas chromatography/mass spectrometry of derivatized amino acids, obtained from hydrolyzed cellular protein, by measuring their 12C content. Several amino acids appeared to be incorporated into the protein to a significant extent, without degradation or conversion. Among these were the aromatic amino acids, L-tyrosine and L-phenylalanine. Using the same replacement approach, their incorporation into PQQ was determined by 1H- and 13C-NMR spectroscopy of purified PQQ obtained from the culture medium. It appeared that the complete carbon skeleton of tyrosine was present, forming the o-quinone and pyrrole-2-carboxylic acid moieties in PQQ, while phenylalanine was not incorporated at all. Starting with L-tyrosine, possible biosynthetic routes to PQQ are discussed.
van Kleef
M A
MA
Laboratory of Microbiology and Enzymology, Delft University of Technology, The Netherlands.
Duine
J A
JA
D000596:Amino Acids / Q000378:metabolism; D001419:Bacteria / Q000378:metabolism*; D001426:Bacterial Proteins / Q000096:biosynthesis; D003067:Coenzymes / Q000096:biosynthesis*; D009682:Magnetic Resonance Spectroscopy; D045542:PQQ Cofactor; D010649:Phenylalanine / Q000378:metabolism; D015363:Quinolones / Q000096:biosynthesis*; D014443:Tyrosine / Q000378:metabolism*
D000596:Amino Acids; D001426:Bacterial Proteins; D003067:Coenzymes; D015363:Quinolones; D014443:Tyrosine; D010649:Phenylalanine; D045542:PQQ Cofactor