PQQ: Biosynthetic studies inMethylobacterium AM1 andHyphomicrobium X using specific13C labeling and NMR |
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| Authors: | David R. Houck John L. Hanners Clifford J. Unkefer Mario A. G. van Kleef Johannis A. Duine |
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| Affiliation: | (1) Los Alamos National Laboratory, University of California, INC-4, M.S. C345, 87545 Los Alamos, NM, USA;(2) Laboratory of Microbiology and Enzymology, Delft University of Technology, Julianalaan 67, 2628 BC Delft, The Netherlands |
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| Abstract: | Using13C labeling and NMR spectroscopy we have determined biosynthetic precursors of pyrroloquinoline quinone (PQQ) in two closely related serine-type methylotrophs,Methylobacterium AM1 andHyphomicrobium X. Analysis of the13C-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. |
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