Characterization of Shewanella oneidensis MtrC: a cell-surface decaheme cytochrome involved in respiratory electron transport to extracellular electron acceptors

Journal Article · Tue Sep 04 04:00:00 EDT 2007 · Journal of Biological Inorganic Chemistry, 12(7):1083-1094

DOI:https://doi.org/10.1007/s00775-007-0278-y· OSTI ID:918455

Hartshorne, Robert S; Jepson, Brian N; Clarke, Thomas A; Field, Sarah J; Fredrickson, Jim K; Zachara, John M; Shi, Liang; Butt, Julea N; Richardson, David

Abstract MtrC is a decaheme c-type cytochrome associated with the outer cell membrane of Fe(III)-respiring species of the Shewanella genus. It is proposed to play a role in anaerobic respiration by mediating electron transfer to extracellular mineral oxides that can serve as terminal electron acceptors. The present work presents the first spectropotentiometric and voltammetric characterization of MtrC, using protein purified from Shewanella oneidensis MR-1. Potentiometric titrations, monitored by UV–vis absorption and electron paramagnetic resonance (EPR) spectroscopy, reveal that the hemes within MtrC titrate over a broad potential range spanning between approximately +100 and approximately *500 mV (vs. the standard hydrogen electrode). Across this potential window the UV– vis absorption spectra are characteristic of low-spin c-type hemes and the EPR spectra reveal broad, complex features that suggest the presence of magnetically spin-coupled lowspin c-hemes. Non-catalytic protein film voltammetry of MtrC demonstrates reversible electrochemistry over a potential window similar to that disclosed spectroscopically. The voltammetry also allows definition of kinetic properties of MtrC in direct electron exchange with a solid electrode surface and during reduction of a model Fe(III) substrate. Taken together, the data provide quantitative information on the potential domain in which MtrC can operate.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (US)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 918455
• Report Number(s): PNNL-SA-57073; KP1501021
• Journal Information: Journal of Biological Inorganic Chemistry, 12(7):1083-1094, Journal Name: Journal of Biological Inorganic Chemistry, 12(7):1083-1094 Journal Issue: 7 Vol. 12
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
ABSORPTION SPECTRA
BINDING ENERGY
CELL MEMBRANES
CYTOCHROMES
Cytochrome c
ELECTRON EXCHANGE
ELECTRON SPIN RESONANCE
ELECTRON TRANSFER
ELECTRONS
SPIN
TRANSPORT
electron paramagnetic resonance
electron transfer
iron respiration
protein film voltammetry