6C8V

X-ray structure of PqqE from Methylobacterium extorquens

Summary for 6C8V

• Entry DOI: 10.2210/pdb6c8v/pdb
• Descriptor: Coenzyme PQQ synthesis protein E, FE2/S2 (INORGANIC) CLUSTER, IRON/SULFUR CLUSTER, ... (4 entities in total)
• Functional Keywords: peptide modifying enzyme, oxidoreductase
• Biological source: Methylobacterium extorquens
• Total number of polymer chains: 1
• Total formula weight: 43477.51

Authors

Gizzi, A.S.,Grove, T.L.,Bonanno, J.B.,Almo, S.C. (deposition date: 2018-01-25, release date: 2018-02-14, Last modification date: 2024-03-13)

Primary citation

Barr, I.,Stich, T.A.,Gizzi, A.S.,Grove, T.L.,Bonanno, J.B.,Latham, J.A.,Chung, T.,Wilmot, C.M.,Britt, R.D.,Almo, S.C.,Klinman, J.P.
X-ray and EPR Characterization of the Auxiliary Fe-S Clusters in the Radical SAM Enzyme PqqE.
Biochemistry, 57:1306-1315, 2018

PubMed Abstract: The Radical SAM (RS) enzyme PqqE catalyzes the first step in the biosynthesis of the bacterial cofactor pyrroloquinoline quinone, forming a new carbon-carbon bond between two side chains within the ribosomally synthesized peptide substrate PqqA. In addition to the active site RS 4Fe-4S cluster, PqqE is predicted to have two auxiliary Fe-S clusters, like the other members of the SPASM domain family. Here we identify these sites and examine their structure using a combination of X-ray crystallography and Mössbauer and electron paramagnetic resonance (EPR) spectroscopies. X-ray crystallography allows us to identify the ligands to each of the two auxiliary clusters at the C-terminal region of the protein. The auxiliary cluster nearest the RS site (AuxI) is in the form of a 2Fe-2S cluster ligated by four cysteines, an Fe-S center not seen previously in other SPASM domain proteins; this assignment is further supported by Mössbauer and EPR spectroscopies. The second, more remote cluster (AuxII) is a 4Fe-4S center that is ligated by three cysteine residues and one aspartate residue. In addition, we examined the roles these ligands play in catalysis by the RS and AuxII clusters using site-directed mutagenesis coupled with EPR spectroscopy. Lastly, we discuss the possible functional consequences that these unique AuxI and AuxII clusters may have in catalysis for PqqE and how these may extend to additional RS enzymes catalyzing the post-translational modification of ribosomally encoded peptides.

PubMed: 29405700
DOI: 10.1021/acs.biochem.7b01097

Experimental method

X-RAY DIFFRACTION (3.2 Å)