The Outreach group POM committee is pleased to announce the ‘Paper of the Month’ for Nov 2017 is a study contributed to by Ling Zhong and Mark Raftery from BMSF, in conjunction with:

Susanne Erdmann, Bernhard Tschitschko, and Ricardo Cavicchioli.

A plasmid from an Antarctic haloarchaeon uses specialized membrane vesicles to disseminate and infect plasmid-free cells

Published in: Nature Microbiology. 2017, 1446-1455

This work is significant because it identifies a plasmid from haloarchaea that challenges the commonly accepted distinctions between viruses and plasmids and supports a strong evolutionary connection between plasmids and virus evolution. 

The major difference between viruses and plasmids is the mechanism of transferring their genomic information between host cells. Here, we describe the archaeal plasmid pR1SE from an Antarctic species of haloarchaea that transfers via a mechanism similar to a virus. pR1SE encodes proteins that are found in regularly shaped membrane vesicles, and the vesicles enclose the plasmid DNA. The released vesicles are capable of infecting a plasmid-free strain, which then gains the ability to produce plasmid-containing vesicles. pR1SE can integrate and replicate as part of the host genome, resolve out with fragments of host

DNA incorporated or portions of the plasmid left behind, form vesicles and transfer to new hosts. The pR1SE mechanism of transfer of DNA could represent the predecessor of a strategy used by viruses to pass on their genomic DNA and fulfil roles in gene exchange, supporting a strong evolutionary connection between plasmids and viruses.

To read more, follow this link:

https://www.nature.com/articles/s41564-017-0009-2

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Fig. 1: Transmission electron micrographs of Hrr. Lacusprofundi R1S1 VLPs.