A Widespread group of large plasmids in methanotrophic archaea

Schoelmerich, M. C.*; Oubouter, H. T.*; Sachdeva, R.*; Penev, P. I.*; 天野 由記   ; West-Roberts, J.*; Welte, C. U.*; Banfield, J. F.*

Schoelmerich, M. C.*; Oubouter, H. T.*; Sachdeva, R.*; Penev, P. I.*; Amano, Yuki; West-Roberts, J.*; Welte, C. U.*; Banfield, J. F.*

Anaerobic methanotrophic archaea (ANME) make energy from the breakdown of methane, an important driver of global warming, yet the extrachromosomal genetic elements that impact the activities of ANME are little understood. Here we describe large plasmids associated with ANME of the Methanoperedens Genus. These have been maintained in two enrichment bioreactors that are highly dominated by different species and associate with species in other anaerobic environments. By manual curation we show that two of the plasmids are large (155,607 bp and 191,912 bp), circular, and replicate bidirectionally. The group of species that carry these plasmids is related to , and and the plasmids occur in the same copy number as the main chromosome. The larger plasmid encodes transporters that potentially enhance access to Ni, which is required for the MCR complex, Co required for the cobalamin cofactor needed for methyltransferases tied to central processes and amino acid uptake. We show that many plasmid genes are actively transcribed, including genes involved in plasmid chromosome maintenance and segregation, a Co/Ni transporter and cell protective proteins. Notably, plasmid-borne genes for a ribosomal protein uL16 and adjacent elongation factor eEF2 are highly expressed. These are not encoded in the host genome, indicating an obligate interdependence between this plasmid and its host. The finding of plasmids of opens the way for the development of genetic vectors that could be used to probe little understood aspects of physiology. Ultimately, this may provide a route to introduce or alter genes that may enhance growth and overall metabolism to accelerate methane oxidation rates.