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Publication Abstract from PubMed

Pyrroloquinoline quinone (PQQ) has received considerable attention due to its numerous important physiological functions. PqqA is a precursor peptide of PQQ with two conserved residues: glutamate and tyrosine. After linkage of the Cgamma; of glutamate and CE of tyrosine by PqqE, these two residues are hypothesized to be cleaved from PqqA by PqqF. The linked glutamate and tyrosine residues are then used to synthesize PQQ. Here, we demonstrated that the pqqF gene is essential for PQQ biosynthesis since deletion of it eliminated the inhibition of prodigiosin production by glucose. We further determined the crystal structure of PqqF, which has a closed clam shell-like shape. The PqqF consists of two halves composed of an N- and a C-terminal lobe. The PqqF-N and PqqF-C lobes form a chamber with the volume of the cavity of 9400 A3. The PqqF structure conforms to the general structure of inverzincins. Compared with the most thoroughly characterized inverzincin insulin-degrading enzyme (IDE), the size of PqqF chamber is markedly smaller, which may define the specificity for its substrate PqqA. Furthermore, the 14 amino acid residue-long tag formed by the N-terminal tag from expression vector precisely protrudes into the counterpart active site; this N-terminal tag occupies the active site and stabilizes the closed, inactive conformation. H48, H52, E129 and H-14 from the N-terminal tag coordinate with the zinc ion. E51 acts as a base catalyst. The observed histidine residue-mediated inhibition may be applicable for the design of a peptide for the inhibition of M16 metalloproteases.

Crystal Structure and Function of PqqF in the Pyrroloquinoline Quinone Biosynthetic Pathway.,Wei Q, Ran T, Ma C, He J, Xu D, Wang W J Biol Chem. 2016 May 26. pii: jbc.M115.711226. PMID:27231346^[1]

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