Chlamydial contribution to anaerobic metabolism during eukaryotic evolution.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 32923644.
- Also identified by DOI 10.1126/sciadv.abb7258 and PMC identifier 7449678.
- Licence recorded as CC BY-NC.
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Abstract
The origin of eukaryotes is a major open question in evolutionary biology. Multiple hypotheses posit that eukaryotes likely evolved from a syntrophic relationship between an archaeon and an alphaproteobacterium based on H<sub>2</sub> exchange. However, there are no strong indications that modern eukaryotic H<sub>2</sub> metabolism originated from archaea or alphaproteobacteria. Here, we present evidence for the origin of H<sub>2</sub> metabolism genes in eukaryotes from an ancestor of the Anoxychlamydiales-a group of anaerobic chlamydiae, newly described here, from marine sediments. Among Chlamydiae, these bacteria uniquely encode genes for H<sub>2</sub> metabolism and other anaerobiosis-associated pathways. Phylogenetic analyses of several components of H<sub>2</sub> metabolism reveal that Anoxychlamydiales homologs are the closest relatives to eukaryotic sequences. We propose that an ancestor of the Anoxychlamydiales contributed these key genes during the evolution of eukaryotes, supporting a mosaic evolutionary origin of eukaryotic metabolism.