The lysis mechanism of the haloarchaeal virus HFTV1.

Tailed bacteriophages can lyse their host with help of the holin-endolysin system. However, for archaeal tailed viruses (arTVs), whose archaeal hosts have a fundamentally different cell envelope, lysis mechanisms are unknown. In this study, we use the model archaeal virus-host system: Haloferax tailed virus 1 (HFTV1), which infects the methanobacteriote Haloferax gibbonsii LR2-5. We identified and characterized the lysis protein GP33, a small membrane protein that has no sequence homology with bacterial holins. Overexpression resulted in cell lysis, and the protein forms foci near the cell envelope. Molecular dynamics simulation suggests that it forms pores from which the lipids are repelled, which might result in cell lysis. Indeed, atomic force microscopy (AFM) showed that GP33 forms pores in membranes, which lead to complete membrane disruption at higher concentrations. With this work, we gain insight into a lysis mechanism from a tailed archaeal virus at the molecular level.