Electron Paramagnetic Resonance Spectroscopic Identification of the Fe-S Clusters in the SPASM Domain-Containing Radical SAM Enzyme PqqE.

ABSTRACT: Pyrroloquinoline quinone (PQQ) is an important redox active quinocofactor produced by a wide variety of bacteria. A key step in PQQ biosynthesis is a carbon-carbon cross-link reaction between glutamate and tyrosine side chains within the ribosomally synthesized peptide substrate PqqA. This reaction is catalyzed by the radical SAM enzyme PqqE. Previous X-ray crystallographic and spectroscopic studies suggested that PqqE, like the other members of the SPASM domain family, contains two auxiliary Fe-S clusters (AuxI and AuxII) in addition to the radical SAM [4Fe-4S] cluster. However, a clear assignment of the electron paramagnetic resonance (EPR) signal of each Fe-S cluster was hindered by the isolation of a His₆-tagged PqqE variant with an altered AuxI cluster. In this work, we are

SUBMITTER: Tao L 

PROVIDER: S-EPMC6959549 | biostudies-literature | 2019 Dec

REPOSITORIES: biostudies-literature