Cytochrome c‐based domain modularity governs genus‐level diversification of electron transfer to dissimilatory nitrite reduction. (11th December 2014)

• Record Type: Journal Article
• Authors: Aas, Finn Erik; Li, Xi; Edwards, James; Hongrø Solbakken, Monica; Deeudom, Manu; Vik, Åshild; Moir, James; Koomey, Michael; Aspholm, Marina
• Is Part Of: Environmental microbiology. Volume 17:Number 6(2015:Jun.)
• Page Start: 2114
• Page End: 2132
• Publication Date: 2014-12-11
• Subjects: Microbial ecology -- Periodicals; Environmental Microbiology -- Periodicals; 579.17
• DOI: 10.1111/1462-2920.12661
• Languages: English
• ISSNs: 1462-2912

Abstract

<abstract abstract-type="main"> <title>Summary</title> <p>The genus <italic>N</italic><italic>eisseria</italic> contains two pathogenic species (<italic>N</italic><italic>. meningitidis</italic> and <italic>N</italic><italic>. gonorrhoeae</italic>) in addition to a number of commensal species that primarily colonize mucosal surfaces in man. Within the genus, there is considerable diversity and apparent redundancy in the components involved in respiration. Here, we identify a unique <italic>c</italic>‐type cytochrome (<italic>c</italic><sub>N</sub>) that is broadly distributed among commensal <italic>N</italic><italic>eisseria</italic>, but absent in the pathogenic species. Specifically, <italic>c</italic><sub>N</sub> supports nitrite reduction in <italic>N</italic><italic>. gonorrhoeae</italic> strains lacking the cytochromes <italic>c</italic><sub>5</sub> and CcoP established to be critical to NirK nitrite reductase activity. The <italic>c</italic>‐type cytochrome domain of <italic>c</italic><sub>N</sub> shares high sequence identity with those localized c‐terminally in <italic>c</italic><sub>5</sub> and CcoP and all three domains were shown to donate electrons directly to NirK. Thus, we identify three distinct but paralogous proteins that donate electrons to NirK. We also demonstrate functionality for a <italic>N</italic><italic>. weaverii</italic> NirK variant with a C‐terminal <italic>c</italic>‐type heme extension. Taken together, modular domain distribution and gene rearrangement events related to these respiratory electron carriers within <italic>N</italic><italic>eisseria</italic> are concordant with major transitions in the macroevolutionary history of the genus. This work emphasizes the importance of denitrification as a selectable trait that may influence speciation and adaptive diversification within this largely host‐restricted bacterial genus.</p> </abstract>