2026/05/23 by Ling-Dong Shi, Petar Penev, Bethany C. Kolody +16 · 1 voice
Environmental Science · Physics and Astronomy · #Archaea #Bacteriophages and microbial interactions #Extrachromosomal DNA #Gene #Horizontal gene transfer #Methane Hydrates and Related Phenomena #Operon #Origins and Evolution of Life #Phylogenetic tree #Phylogenetics #Ribosomal RNA
paper · doi:10.64898/2026.05.22.727314
published in bioRxiv (Cold Spring Harbor Laboratory) (Cold Spring Harbor Laboratory)
openalex publication_date 2026/05/23 · openalex created_date 2026/05/25 · openalex updated_date 2026/07/14
Abstract Borgs are giant linear extrachromosomal elements (ECEs) of methane-oxidizing Methanoperedens archaea whose evolutionary origin and ecosystem distribution remain unknown. Here we detected 240 Borgs in diverse saline, soil, and freshwater ecosystems. 27 encode methyl-coenzyme M reductases central to methane metabolism, eight have full rRNA operons related to those of Methanoperedens , and some contain up to four ribosomal proteins. We also identified 323 mini-Borgs whose proteome content and gene phylogenies classify as a distinct ECE type. Based on 105 complete and near-complete genomes, Borgs and mini-Borgs share core genes in conserved order, indicating common ancestry. Phylogenetic and diversity analyses suggest that Borgs evolved via gene acquisition into a backbone inherited from mini-Borgs. This evolutionary trajectory mirrors those proposed for giant viruses of both eukaryotes and bacteria.