PQQ: biosynthetic studies in Methylobacterium AM1 and Hyphomicrobium X using specific 13C labeling and NMR.
Using 13C labeling and NMR spectroscopy we have determined biosynthetic precursors of pyrroloquinoline quinone (PQQ) in two closely related serine-type methylotrophs, Methylobacterium AM1 and Hyphomicrobium X. Analysis of the 13C-labeling data revealed that PQQ is constructed from two amino acids: the portion containing N-6,C-7, 8, 9 and the two carboxylic acid groups, C-7' and 9', is derived-intact -from glutamate. The remaining portion is derived from tyrosine; the phenol side chain provides the six carbons of the ring containing the orthoquinone, whereas internal cyclization of the amino acid backbone forms the pyrrole-2-carboxylic acid moiety. This is analogous to the cyclization of dopaquinone to form dopachrome. Dopaquinone is a product of the oxidation of tyrosine (via dopa) in reactions catalyzed by monophenol monooxygenase (EC 1.14.18.1). Starting with tyrosine and glutamate, we will discuss possible biosynthetic routes to PQQ.
Houck
D R
DR
Los Alamos National Laboratory, University of California 87545.
Hanners
J L
JL
Unkefer
C J
CJ
van Kleef
M A
MA
Duine
J A
JA
D000596:Amino Acids / Q000378:metabolism; D002247:Carbon Isotopes; D003067:Coenzymes / Q000096:biosynthesis*; D004792:Enzyme Precursors / Q000096:biosynthesis*; D000431:Ethanol / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D000432:Methanol / Q000378:metabolism; D008772:Methylococcaceae / Q000201:enzymology*; D015394:Molecular Structure; D045542:PQQ Cofactor; D011549:Pseudomonas / Q000187:drug effects / Q000201:enzymology; D015363:Quinolones / Q000096:biosynthesis*; D014443:Tyrosine / Q000378:metabolism
D000596:Amino Acids; D002247:Carbon Isotopes; D003067:Coenzymes; D004792:Enzyme Precursors; D015363:Quinolones; D000431:Ethanol; D014443:Tyrosine; D045542:PQQ Cofactor; D000432:Methanol