RRC ID 80592
Author Gulay A, Fournier G, Smets BF, Girguis PR.
Title Proterozoic Acquisition of Archaeal Genes for Extracellular Electron Transfer: A Metabolic Adaptation of Aerobic Ammonia-Oxidizing Bacteria to Oxygen Limitation.
Journal Mol Biol Evol
Abstract Many aerobic microbes can utilize alternative electron acceptors under oxygen-limited conditions. In some cases, this is mediated by extracellular electron transfer (or EET), wherein electrons are transferred to extracellular oxidants such as iron oxide and manganese oxide minerals. Here, we show that an ammonia-oxidizer previously known to be strictly aerobic, Nitrosomonas communis, may have been able to utilize a poised electrode to maintain metabolic activity in anoxic conditions. The presence and activity of multiheme cytochromes in N. communis further suggest a capacity for EET. Molecular clock analysis shows that the ancestors of β-proteobacterial ammonia oxidizers appeared after Earth's atmospheric oxygenation when the oxygen levels were >10-4pO2 (present atmospheric level [PAL]), consistent with aerobic origins. Equally important, phylogenetic reconciliations of gene and species trees show that the multiheme c-type EET proteins in Nitrosomonas and Nitrosospira lineages were likely acquired by gene transfer from γ-proteobacteria when the oxygen levels were between 0.1 and 1 pO2 (PAL). These results suggest that β-proteobacterial EET evolved during the Proterozoic when oxygen limitation was widespread, but oxidized minerals were abundant.
Volume 40(8)
Published 2023-8-3
DOI 10.1093/molbev/msad161
PII 7223884
PMID 37440531
PMC PMC10415592
MeSH Ammonia* / metabolism Electrons Gammaproteobacteria* / metabolism Genes, Archaeal Oxidation-Reduction Oxygen Phylogeny
General Microbes JCM 30413