Purification and magneto-optical spectroscopic characterization of cytoplasmic membrane and outer membrane multiheme c-type cytochromes from Shewanella frigidimarina NCIMB400

Field, Sarah J., Dobbin, Paul S., Cheesman, Myles R., Watmough, Nicholas J., Thomson, Andrew J. and Richardson, David J. (2000) Purification and magneto-optical spectroscopic characterization of cytoplasmic membrane and outer membrane multiheme c-type cytochromes from Shewanella frigidimarina NCIMB400. The Journal of Biological Chemistry, 275 (12). pp. 8515-8522. ISSN 1083-351X

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Abstract

Two membranous c-type cytochromes from the Fe(III)-respiring bacterium Shewanella frigidimarina NCIMB400, CymA and OmcA, have been purified and characterized by W-visible, magnetic circular dichroism, and electron paramagnetic resonance spectroscopies. The 20-kDa CymA is a member of the NapC/NirT family of multiheme cytochromes, which are invariably anchored to the cytoplasmic membrane of Gram-negative bacteria, and are postulated to mediate electron flow between quinols and periplasmic redox proteins. CymA was found to contain four low-spin c-hemes, each with bis-His axial ligation, and midpoint reduction potentials of +10, -108, -136, and -229 mV, The 85-kDa OmcA is located at the outer membrane of S, frigidimarina NCIMB400, and as such might function as a terminal reductase via interaction with insoluble Fe(III) substrates, This putative role is supported by the finding that the protein was released into solution upon incubation of harvested intact cells at 25 degrees C, suggesting an attachment to the exterior face of the outer membrane, OmcA was revealed by magneto-optical spectrocopies to contain 10 low-spin bis-His ligated c-hemes, with the redox titer indicating two sets of near iso-potential components centered at -243 and -324 mV.

Item Type: Article
Faculty \ School: Faculty of Science > School of Chemistry
Faculty of Science > School of Biological Sciences
Depositing User: Rachel Smith
Date Deposited: 10 May 2011 10:53
Last Modified: 10 Jan 2019 09:30
URI: https://ueaeprints.uea.ac.uk/id/eprint/30101
DOI: 10.1074/jbc.275.12.8515

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