A trans‐outer membrane porin‐cytochrome protein complex for extracellular electron transfer by Geobacter sulfurreducens PCA. Issue 6 (24th September 2014)

• Record Type: Journal Article
• Authors: Liu, Yimo; Wang, Zheming; Liu, Juan; Levar, Caleb; Edwards, Marcus J.; Babauta, Jerome T.; Kennedy, David W.; Shi, Zhi; Beyenal, Haluk; Bond, Daniel R.; Clarke, Thomas A.; Butt, Julea N.; Richardson, David J.; Rosso, Kevin M.; Zachara, John M; Fredrickson, James K.; Shi, Liang
• Is Part Of: Environmental microbiology reports. Volume 6:Issue 6(2014)
• Page Start: 776
• Page End: 785
• Publication Date: 2014-09-24
• Subjects: Microbial ecology -- Periodicals; Environmental Microbiology -- Periodicals; Electronic journals; 579.17
• DOI: 10.1111/1758-2229.12204
• Languages: English
• ISSNs: 1758-2229

Abstract

<abstract abstract-type="main"> <title>Summary</title> <p>The multi‐heme, outer membrane <italic>c</italic>‐type cytochrome (<italic>c</italic>‐Cyt) OmcB of <italic>G</italic><italic>eobacter sulfurreducens</italic> was previously proposed to mediate electron transfer across the outer membrane. However, the underlying mechanism has remained uncharacterized. In <italic>G</italic><italic>. sulfurreducens</italic>, the <italic>omcB</italic> gene is part of two tandem four‐gene clusters, each is predicted to encode a transcriptional factor (OrfR/OrfS), a porin‐like outer membrane protein (OmbB/OmbC), a periplasmic <italic>c‐</italic>type cytochrome (OmaB/OmaC) and an outer membrane <italic>c</italic>‐Cyt (OmcB/OmcC) respectively. Here, we showed that OmbB/OmbC, OmaB/OmaC and OmcB/OmcC of <italic>G</italic><italic>. sulfurreducens</italic> PCA formed the porin‐cytochrome (Pcc) protein complexes, which were involved in transferring electrons across the outer membrane. The isolated Pcc protein complexes reconstituted in proteoliposomes transferred electrons from reduced methyl viologen across the lipid bilayer of liposomes to Fe(III)‐citrate and ferrihydrite. The <italic>pcc</italic> clusters were found in all eight sequenced <italic>G</italic><italic>eobacter</italic> and 11 other bacterial genomes from six different phyla, demonstrating a widespread distribution of Pcc protein complexes in phylogenetically diverse bacteria. Deletion of <italic>ombB‐omaB‐omcB‐orfS‐ombC‐omaC‐omcC</italic> gene clusters had no impact on the growth of <italic>G</italic><italic>. sulfurreducens</italic> PCA with fumarate but diminished the ability of <italic>G</italic><italic>. sulfurreducens</italic> PCA to reduce Fe(III)‐citrate and ferrihydrite. Complementation with the <italic>ombB‐omaB‐omcB</italic> gene cluster restored the ability of <italic>G</italic><italic>. sulfurreducens</italic> PCA to reduce Fe(III)‐citrate and ferrihydrite.</p> </abstract>