Giant extrachromosomal elements found in archaea metabolizing methane

A team of researchers from the University of California, Colorado State University, and the Lawrence Berkeley National Laboratory have discovered a new type of extrachromosomal element (ECE) living inside an archaea that metabolizes methane. The article describing their findings is available on the bioRxiv preprint server.

ECEs are types of DNA that exist outside of chromosomes. They include viruses and plasmids and generally confer some benefit to the host. Along with viruses, ECEs tend to help resist attack by bacteria. In this new study, the researchers were looking for STEs that could be useful in breaking down methane in soil, which is one way to reduce greenhouse gas emissions on farms. Their job was to dig into the ground and collect samples of the organisms that lived there. As part of this effort, they came across an EPR they had never seen before. The most remarkable feature of the ECE was its size; the samples had between 600,000 and 1 million base pairs. They were so large that they were almost a third the length of the DNA of their host, an archeon called Methanoperedens. The researchers also found several varieties of CEE, which they named after colors, such as “lilac” or “olive.” To date, they have found 23 variations.

The researchers found that it had distinct base pairs at each end of its strands and also replication sites. They also found pieces of the host genome in the ECE strands. The team then searched the database comparing the new ECE with other slime DNAs and found several matches. The researchers suggest that the ECE obtains DNA extracts from other organisms it encounters, which led them to name it Borg, after the cyborgs of fame from “Star Trek”.

The researchers noted that collecting pieces of DNA from other organisms would require some effort, suggesting there was a purpose. They theorize that the Borgs research and use DNA that helps them oxidize methane. They further suggest that their large size suggests that they may have existed in the past as plasmids or viruses.

© 2021 Science X Network