Viral Hijack of Filamentous Surface Structures in Archaea and Bacteria

Abstract

The bacterial and archaeal cell surface is decorated with filamentous surface structures that are used for different functions, such as motility, DNA exchange and biofilm formation. Viruses hijack these structures and use them to ride to the cell surface for successful entry. In this review, we describe currently known mechanisms for viral attachment, translocation, and entry via filamentous surface structures. We describe the different mechanisms used to exploit various surface structures bacterial and archaeal viruses. This overview highlights the importance of filamentous structures at the cell surface for entry of prokaryotic viruses.

Halorubrum pleomorphic virus-6 Membrane Fusion Is Triggered by an S-Layer Component of Its Haloarchaeal Host

“…Viruses have developed various strategies to cross the host-cell envelope and infect their target cell. These vary depending on the structural and biochemical nature of their host [9,59,60]. Although there is relatively little information about the entry of archaeal viruses into host cells, it seems that some archaeal viruses rely on processes analogous to bacterial or eukaryotic virus counterparts [10,33].…”

“…However, since the haloarchaeal hostcell structures serving as receptors for viruses have not been fully characterized, a more complete comprehension of virus-host interactions in archaea is paramount to understand the evolutionary pressures on viruses to adapt to their cellular receptors. The haloarchaeal S-layer is commonly mentioned as one of the most probable viral receptors, considering its role as the first barrier that viruses must overcome before they can penetrate the cellular membrane [9,10,26]. Based on the molecular structures obtained for haloarchaeal pleomorphic viruses, a particular mechanism has been proposed; the V-shaped VP4-like protein is therein believed to change its conformation into an elongated structure upon binding to the host S-layer [33].…”

“…Pleolipoviruses infect Haloarchaea, members of the Euryarchaeota phylum that live in hypersaline environments ranging from 10% salinity to salt saturation [8]. Yet, the entry mechanisms of archaeal viruses are in general poorly characterized, but it is likely that archaeal viruses, like their bacterial counterparts, recognize and attach to cell wall components, such as S-layer proteins, sugar moieties, or filamentous surface structures, such as pili [9][10][11][12][13][14]. In most haloarchaea, the sole constituent of the cell wall is the proteinaceous surface layer (S-layer) that encloses the cellular membrane and functions as a protective coat that covers the whole cell [15][16][17][18].…”

Characterization of Blf4, an Archaeal Lytic Virus Targeting a Member of the Methanomicrobiales

“…The finding that Blf4 attaches to both M. bourgensis E02.3 s cell surface and its appendages (Figure 4, Supplementary Figure S2) suggests that the virus might be facultatively flagellotropic. This would increase the target radius (up to 10-fold) and allow for movement of the virus from the flagella towards a second receptor on the cell surface [74,75]. Such facultative flagellotropy raises the question about the array of epitopes Blf4 recognizes.…”

Viruses of Microbes 2020: The Latest Conquest on Viruses of Microbes

“…In this Special Issue, recent advances in the field of microbial virology are collected. Two reviews summarize the novel developments in understanding RNA viruses of aquatic eukaryotes [ 1 ] and on entry mechanisms of prokaryotic viruses [ 2 ]. Comparison between different viruses requires genomic evaluation tools, such as the VIRIDIC tool presented in this issue [ 3 ].…”