9EOV

Crystal structure of domains I and II from the outer membrane cytochrome MtrC

Summary for 9EOV

• Entry DOI: 10.2210/pdb9eov/pdb
• Descriptor: Extracellular iron oxide respiratory system surface decaheme cytochrome c component MtrC, HEME C, MAGNESIUM ION, ... (5 entities in total)
• Functional Keywords: multiheme cytochrome, shewanella oneidensis, truncation, extracellular electron transfer, redox., electron transport
• Biological source: Shewanella oneidensis MR-1
• Total number of polymer chains: 1
• Total formula weight: 37821.24

Authors

Nash, B.W.,Morales Florez, A.,Lockwood, C.W.J.,Edwards, M.J.,Butt, J.N.,Clarke, T.A. (deposition date: 2024-03-15, release date: 2025-08-13)

Primary citation

Morales-Florez, A.,Lockwood, C.W.J.,Nash, B.W.,Edwards, M.J.,van Wonderen, J.H.,Sachdeva, A.,Butt, J.N.,Clarke, T.A.
Extracellular catalysis of environmental substrates by Shewanella oneidensis MR-1 occurs via active sites on the C-terminal domains of MtrC.
Protein Sci., 34:e70243-e70243, 2025

PubMed Abstract: The Gram-negative Shewanellaceae family is well known for its ability to transfer catabolically derived electrons to extracellular terminal electron acceptors through electron conduits that permeate the outer membrane. The primary conduit is MtrCAB, a trimeric porin-cytochrome complex that contains the cell surface exposed decaheme cytochrome MtrC. This donates electrons to extracellular substrates, including OmcA, soluble metals, organic electron shuttles, and insoluble metal oxides. However, it is not clear whether this broad substrate specificity requires specific sites for binding and reduction, or whether reduction occurs through non-specific interactions near exposed hemes on the cytochrome surface. Shewanella oneidensis MtrC is composed of four domains, with the hemes closely packed and distributed evenly between domains II and IV. The domains are arranged to allow electron transport across the cytochrome via interdomain electron transfer, but the significance of this conserved feature is not understood. Here we use site-directed mutagenesis to generate an MtrC variant that is comprised only of domains I and II (MtrC). The properties of this MtrC are effectively identical to domains I and II of full-length MtrC. Whole-cell assays revealed that S. oneidensis cells replacing full-length MtrC with MtrC had significantly lower rates of OmcA, flavin mononucleotide, and Fe(III) citrate reduction. Our results demonstrate that MtrC domains III and IV contain sites for association of specific substrates, enabling the reduction of extracellular electron acceptors in S. oneidensis.

PubMed: 40725986
DOI: 10.1002/pro.70243

Experimental method

X-RAY DIFFRACTION (1.8 Å)