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Publication Abstract from PubMed

Mutational analysis of the pyridoxal 5'-phosphate (PLP)-dependent enzyme PctV has been carried out to elucidate the multi-step reaction mechanism for the formation of 3-aminobenzoate (3-ABA) from 3-dehydroshikimate (3-DSA). The results revealed that the introduction of a K276R mutation led to the accumulation of a quinonoid intermediate with an absorption maximum of 580 nm following the reaction of pyridoxamine 5'-phosphate (PMP) with 3-DSA. Furthermore, the chemical structure of this intermediate was supported by X-ray crystallographic analysis of the complex formed between the K276R mutant and the quinonoid intermediate. These results clearly show that a quinonoid intermediate is involved in the formation of 3-ABA, and also indicate that the Lys276 residue in the active site of the PctV enzyme plays multiple roles including acid/base catalysis during the dehydration reaction of the quinonoid intermediate, as well as assisting in the PMP formation and aminotransfer reaction.

Mechanism-based Trapping of the Quinonoid Intermediate Using the K276R Mutant of PLP-Dependent 3-Aminobenzoate Synthase PctV in the Biosynthesis of Pactamycin.,Hirayama A, Miyanaga A, Kudo F, Eguchi T Chembiochem. 2015 Oct 1. doi: 10.1002/cbic.201500426. PMID:26426567^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.