Demonstration That the Radical S-Adenosylmethionine (SAM) Enzyme PqqE Catalyzes de Novo Carbon-Carbon Cross-linking within a Peptide Substrate PqqA in the Presence of the Peptide Chaperone PqqD.

Authors

Ian Barr, University of California, BerkeleyFollow
John A. Latham, University of California, BerkeleyFollow
Anthony T. Iavarone, University of California, Berkeley
Teera Chantarojsiri, University of California, Berkeley
Jennifer D. Hwang, University of California, Berkeley
Judith P. Klinman, University of California, BerkeleyFollow

Department

Natural Sciences and Mathematics

Document Type

Article

Source

Journal of Biochemistry

Publication Date

4-22-2016

ISSN

1083-351X

Volume

291

Issue

17

First Page

8877

Last Page

8884

Abstract

The radical S-adenosylmethionine (SAM) protein PqqE is predicted to function in the pyrroloquinoline quinone (PQQ) biosynthetic pathway via catalysis of carbon-carbon bond formation between a glutamate and tyrosine side chain within the small peptide substrate PqqA. We report here that PqqE activity is dependent on the accessory protein PqqD, which was recently shown to bind PqqA tightly. In addition, PqqE activity in vitro requires the presence of a flavodoxin- and flavodoxin reductase-based reduction system, with other reductants leading to an uncoupled cleavage of the co-substrate SAM. These results indicate that PqqE, in conjunction with PqqD, carries out the first step in PQQ biosynthesis: a radical-mediated formation of a new carbon-carbon bond between two amino acid side chains on PqqA.

PubMed ID

26961875

Rights

© 2016 by The American Society for Biochemistry and Molecular Biology, Inc.