Toggle Main Menu Toggle Search

Open Access padlockePrints

Quinol-cytochrome c Oxidoreductase and Cytochrome c4 Mediate Electron Transfer during Selenate Respiration in Thauera selenatis

Lookup NU author(s): Dr Elisabeth Lowe, Elizabeth Dridge, Charles Debieux, Dr Ian Singleton, Professor Rick Lewis, Dr Clive Butler

Downloads

Full text for this publication is not currently held within this repository. Alternative links are provided below where available.


Abstract

Selenatereductase(SER) from Thaueraselenatis is a periplasmic enzyme that has been classified as a type II molybdoenzyme. The enzyme comprises three subunits SerABC, where SerC is an unusual b-heme cytochrome. In the present work the spectropotentiometric characterization of the SerC component and the identification of redox partners to SER are reported. The mid-point redox potential of the b-heme was determined by optical titration (E-m + 234 +/- 10 mV). A profile of periplasmic c-type cytochromes expressed in T. selenatis under selenate respiring conditions was undertaken. Two c-type cytochromes were purified (similar to 24 and similar to 6 kDa), and the 24-kDa protein (cytc-Ts4) was shown to donate electrons to SerABC in vitro. Protein sequence of cytc-Ts4 was obtained by N-terminal sequencing and liquid chromatography-tandem mass spectrometry analysis, and based upon sequence similarities, was assigned as a member of cytochrome c(4) family. Redox potentiometry, combined with UV-visible spectroscopy, showed that cytc-Ts4 is a diheme cytochrome with a redox potential of + 282 +/- 10 mV, and both hemes are predicted to have His-Met ligation. To identify the membrane-bound electron donors to cytc-Ts4, growth of T. selenatis in the presence of respiratory inhibitors was monitored. The specific quinol-cytochrome c oxidoreductase (QCR) inhibitors myxothiazol and antimycin A partially inhibited selenate respiration, demonstrating that some electron flux is via the QCR. Electron transfer via a QCR and a diheme cytochrome c(4) is a novel route for a member of the DMSO reductase family of molybdoenzymes.


Publication metadata

Author(s): Lowe EC, Bydder S, Hartshorne RS, Tape HLU, Dridge EJ, Debieux CM, Paszkiewicz K, Singleton I, Lewis RJ, Santini JM, Richardson DJ, Butler CS

Publication type: Article

Publication status: Published

Journal: Journal of Biological Chemistry

Year: 2010

Volume: 285

Issue: 24

Pages: 18433-18442

Print publication date: 11/06/2010

ISSN (print): 0021-9258

ISSN (electronic): 1083-351X

Publisher: American Society for Biochemistry and Molecular Biology, Inc.

URL: http://dx.doi.org/10.1074/jbc.M110.115873

DOI: 10.1074/jbc.M110.115873


Altmetrics

Altmetrics provided by Altmetric


Share