Nitrogen pathway gene cluster

PQQ is derived from a peptide precursor that contains conserved glutamate (13) and tyrosine (76) residues. All carbon and nitrogen atoms of the precursor amino acids are incorporated into the product (44). Gene clusters involved in this pathway have been studied in considerable detail. The X-ray structure of the enzyme that catalyzes the final reaction step has been determined, and reaction mechanisms have been proposed on that basis (45). However, details of the biosynthetic pathway are still incompletely understood. 

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