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Title: A Functional Description of CymA, an Electron Transfer Hub Supporting Anaerobic Respiratory Flexibility in Shewanella

Abstract

CymA is a member of the NapC/NirT family of quinol dehydrogenases. Essential for the anaerobic respiratory flexibility of shewanellae, CymA transfers electrons from menaquinol to various dedicated systems for the reduction of terminal electron acceptors including fumarate and insoluble minerals of Fe(III). Spectroscopic characterization of CymA from Shewanella oneidensis MR-1 identifies three low-spin His/His coordinated c-hemes and a single high-spin c-heme with His/H{sub 2}O coordination lying adjacent to the quinol binding site. At pH 7, binding of the menaquinol analogue, 2-heptyl-4-hydroxyquinoline-N-oxide, does not alter the mid-point potentials of the high-spin (ca. {approx}240 mV) and low-spin (ca. {approx}110, {approx}190 and {approx}265 mV) hemes that appear biased to transfer electrons from the high- to low-spin centres following quinol oxidation. CymA is reduced with menadiol (E{sub m} = {approx} 80 mV) in the presence of NADH (E{sub m} = {approx} 320 mV) and an NADH:menadione oxidoreductase, but not by menadiol alone. In cytoplasmic membranes reduction of CymA may then require the thermodynamic driving force from NADH, formate or H{sub 2} oxidation as the redox poise of the menaquinol pool in isolation is insufficient. Spectroscopic studies suggest that CymA requires a nonheme cofactor for quinol oxidation and that the reduced enzyme forms a 1:1more » complex with its redox partner Fcc{sub 3}. The implications for CymA supporting the respiratory flexibility of shewanellae are discussed.« less

Authors:
; ; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1045102
Report Number(s):
PNNL-SA-87065
Journal ID: ISSN 0006-2936; BIJOAK; KP1702030; TRN: US201214%%930
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Journal Name:
Biochemical Journal
Additional Journal Information:
Journal Volume: 444; Journal Issue: 3; Journal ID: ISSN 0006-2936
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; 60 APPLIED LIFE SCIENCES; BINDING ENERGY; ELECTRON TRANSFER; ELECTRONS; ENZYMES; FLEXIBILITY; FORMATES; FUNCTIONALS; MEMBRANES; OXIDATION; OXIDOREDUCTASES; THERMODYNAMICS; VALENCE; cytochrome; magnetic circular dichroism; electron paramagnetic resonance; quinol

Citation Formats

Marritt, Sophie, Lowe, Thomas G., Bye, Jordan, McMillan, Duncan G., Shi, Liang, Fredrickson, Jim K., Zachara, John M., Richardson, David J., Cheesman, Myles R., Jeuken, Lars J., and Butt, Julea N. A Functional Description of CymA, an Electron Transfer Hub Supporting Anaerobic Respiratory Flexibility in Shewanella. United States: N. p., 2012. Web. doi:10.1042/BJ20120197.
Marritt, Sophie, Lowe, Thomas G., Bye, Jordan, McMillan, Duncan G., Shi, Liang, Fredrickson, Jim K., Zachara, John M., Richardson, David J., Cheesman, Myles R., Jeuken, Lars J., & Butt, Julea N. A Functional Description of CymA, an Electron Transfer Hub Supporting Anaerobic Respiratory Flexibility in Shewanella. United States. doi:10.1042/BJ20120197.
Marritt, Sophie, Lowe, Thomas G., Bye, Jordan, McMillan, Duncan G., Shi, Liang, Fredrickson, Jim K., Zachara, John M., Richardson, David J., Cheesman, Myles R., Jeuken, Lars J., and Butt, Julea N. Fri . "A Functional Description of CymA, an Electron Transfer Hub Supporting Anaerobic Respiratory Flexibility in Shewanella". United States. doi:10.1042/BJ20120197.
@article{osti_1045102,
title = {A Functional Description of CymA, an Electron Transfer Hub Supporting Anaerobic Respiratory Flexibility in Shewanella},
author = {Marritt, Sophie and Lowe, Thomas G. and Bye, Jordan and McMillan, Duncan G. and Shi, Liang and Fredrickson, Jim K. and Zachara, John M. and Richardson, David J. and Cheesman, Myles R. and Jeuken, Lars J. and Butt, Julea N.},
abstractNote = {CymA is a member of the NapC/NirT family of quinol dehydrogenases. Essential for the anaerobic respiratory flexibility of shewanellae, CymA transfers electrons from menaquinol to various dedicated systems for the reduction of terminal electron acceptors including fumarate and insoluble minerals of Fe(III). Spectroscopic characterization of CymA from Shewanella oneidensis MR-1 identifies three low-spin His/His coordinated c-hemes and a single high-spin c-heme with His/H{sub 2}O coordination lying adjacent to the quinol binding site. At pH 7, binding of the menaquinol analogue, 2-heptyl-4-hydroxyquinoline-N-oxide, does not alter the mid-point potentials of the high-spin (ca. {approx}240 mV) and low-spin (ca. {approx}110, {approx}190 and {approx}265 mV) hemes that appear biased to transfer electrons from the high- to low-spin centres following quinol oxidation. CymA is reduced with menadiol (E{sub m} = {approx} 80 mV) in the presence of NADH (E{sub m} = {approx} 320 mV) and an NADH:menadione oxidoreductase, but not by menadiol alone. In cytoplasmic membranes reduction of CymA may then require the thermodynamic driving force from NADH, formate or H{sub 2} oxidation as the redox poise of the menaquinol pool in isolation is insufficient. Spectroscopic studies suggest that CymA requires a nonheme cofactor for quinol oxidation and that the reduced enzyme forms a 1:1 complex with its redox partner Fcc{sub 3}. The implications for CymA supporting the respiratory flexibility of shewanellae are discussed.},
doi = {10.1042/BJ20120197},
journal = {Biochemical Journal},
issn = {0006-2936},
number = 3,
volume = 444,
place = {United States},
year = {2012},
month = {6}
}