Microbiology & Virology

Culexarchaeia, A Novel Archaeal Class Of Anaerobic Generalists Inhabiting Geothermal Environments

By Keith Cowing
Status Report
February 2, 2023
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Culexarchaeia, A Novel Archaeal Class Of Anaerobic Generalists Inhabiting Geothermal Environments
Biogeography of Culexarchaeia. Sites from where Culexarchaeia MAGs were recovered and where 16S rRNA gene sequences have been detected. A full list of samples and associated metadata can be found in Supplementary File 8. Yellowstone map modified from (97), GBS picture modified from (18), and JZ picture modified from (25). Guaymas Basin image courtesy of the Woods Hole Oceanographic Institution. — biorxiv.org

Geothermal environments, including terrestrial hot springs and deep-sea hydrothermal sediments, often contain many poorly understood lineages of archaea.

Here, we recovered ten metagenome-assembled genomes (MAGs) from geothermal sediments and propose that they constitute a new archaeal class within the TACK superphylum, “Candidatus Culexarchaeia”, named after the Culex Basin in Yellowstone National Park.

Culexarchaeia harbor distinct sets of proteins involved in key cellular processes that are either phylogenetically divergent or are absent from other closely related TACK lineages, with a particular divergence in cell division and cytoskeletal proteins. Metabolic reconstruction revealed that Culexarchaeia have the capacity to metabolize a wide variety of organic and inorganic substrates.

Notably, Culexarchaeia encode a unique modular, membrane associated, and energy conserving [NiFe]-hydrogenase complex that potentially interacts with heterodisulfide reductase (Hdr) subunits. Comparison of this [NiFe]-hydrogenase complex with similar complexes from other archaea suggests that interactions between membrane associated [NiFe]-hydrogenases and Hdr may be more widespread than previously appreciated in both methanogenic and non-methanogenic lifestyles.

The analysis of Culexarchaeia further expands our understanding of the phylogenetic and functional diversity of lineages within the TACK superphylum and the ecology, physiology, and evolution of these organisms in extreme environments.

Anthony J. Kohtz, Zackary J. Jay, Mackenzie Lynes, Viola Krukenberg, Roland Hatzenpichler



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