Extracellular catalysis of environmental substrates by Shewanella oneidensis MR-1 occurs via active sites on the C-terminal domains of MtrC

Morales Florez, Alejandro, Lockwood, Colin, Nash, Benjamin, Edwards, Marcus J., van Wonderen, Jessica H., Sachdeva, Amit, Butt, Julea N. and Clarke, Tom (2025) Extracellular catalysis of environmental substrates by Shewanella oneidensis MR-1 occurs via active sites on the C-terminal domains of MtrC. Protein Science, 34 (8). ISSN 1469-896X

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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 DI,II). The properties of this MtrC DI,II 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 DI,II 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.

Item Type:	Article
Additional Information:	DATA AVAILABILITY STATEMENT: The data that support the findings of this study are openly available in Figshare at https://figshare.com/, reference number 10.6084/m9.figshare.29516924. FUNDING INFORMATION: This work was funded by the UKRI Biotechnology and Biological Sciences Research Council Norwich Research Park Biosciences Doctoral Training Partnership (BB/T008717/1), Focused Research Award (BB/X011453/1) and Leverhulme Trust Research Project Grant (RPG-2020-085).
Uncontrolled Keywords:	shewanella,c-type cytochrome,electron transfer,flavin,heme chain,microbe–mineral interface,molecular biology,biochemistry ,/dk/atira/pure/subjectarea/asjc/1300/1312
Faculty \ School:	Faculty of Science > School of Biological Sciences Faculty of Science > School of Chemistry, Pharmacy and Pharmacology Faculty of Science
UEA Research Groups:	Faculty of Science > Research Groups > Chemistry of Life Processes Faculty of Science > Research Groups > Centre for Photonics and Quantum Science Faculty of Science > Research Groups > Wolfson Centre for Advanced Environmental Microbiology Faculty of Science > Research Groups > Molecular Microbiology Faculty of Science > Research Groups > Energy Materials Laboratory Faculty of Science > Research Groups > Chemistry of Light and Energy Faculty of Science > Research Centres > Centre for Molecular and Structural Biochemistry
Related URLs:	http://www.scopus.com/inward/record.url?...
Depositing User:	LivePure Connector
Date Deposited:	06 Aug 2025 08:30
Last Modified:	22 Aug 2025 00:49
URI:	https://ueaeprints.uea.ac.uk/id/eprint/100058
DOI:	10.1002/pro.70243

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