| first insights into the entry process of hyperthermophilic archaeal viruses. | a decisive step in a virus infection cycle is the recognition of a specific receptor present on the host cell surface, subsequently leading to the delivery of the viral genome into the cell interior. until now, the early stages of infection have not been thoroughly investigated for any virus infecting hyperthermophilic archaea. here, we present the first study focusing on the primary interactions between the archaeal rod-shaped virus sulfolobus islandicus rod-shaped virus 2 (sirv2) (family rudiv ... | 2013 | 24089554 |
| genomics and biology of rudiviruses, a model for the study of virus-host interactions in archaea. | archaeal viruses, especially viruses that infect hyperthermophilic archaea of the phylum crenarchaeota, constitute one of the least understood parts of the virosphere. however, owing to recent substantial research efforts by several groups, archaeal viruses are starting to gradually reveal their secrets. in the present review, we summarize the current knowledge on one of the emerging model systems for studies on crenarchaeal viruses, the rudiviridae. we discuss the recent advances towards unders ... | 2013 | 23356326 |
| insights into a viral lytic pathway from an archaeal virus-host system. | archaeal host cells infected by sulfolobus turreted icosahedral virus (stiv) and sulfolobus islandicus rod-shaped virus 2 (sirv2) produce unusual pyramid-like structures on the cell surface prior to virus-induced cell lysis. this viral lysis process is distinct from known viral lysis processes associated with bacterial or eukaryal viruses. the stiv protein c92 and the sirv2 protein 98 are the only viral proteins required for the formation of the pyramid lysis structures of stiv and sirv2, respec ... | 2013 | 23221563 |
| virology. a virus that infects a hyperthermophile encapsidates a-form dna. | extremophiles, microorganisms thriving in extreme environmental conditions, must have proteins and nucleic acids that are stable at extremes of temperature and ph. the nonenveloped, rod-shaped virus sirv2 (sulfolobus islandicus rod-shaped virus 2) infects the hyperthermophilic acidophile sulfolobus islandicus, which lives at 80°c and ph 3. we have used cryo-electron microscopy to generate a three-dimensional reconstruction of the sirv2 virion at ~4 angstrom resolution, which revealed a previousl ... | 2015 | 25999507 |
| functional characterization of a conserved archaeal viral operon revealing single-stranded dna binding, annealing and nuclease activities. | the majority of archaeal viral genes are of unknown function hindering our understanding of the virus life cycle and viral interactions with their host. here, we first describe functional characterization of orf131b (gp17) and orf436 (gp18) of sulfolobus islandicus rod-shaped virus 2 (sirv2), both encoding proteins of unknown function and forming an operon with orf207 (gp19). sirv2 gp17 was found to be a single-stranded dna (ssdna) binding protein different in structure from all previously chara ... | 2015 | 25828870 |
| biochemical characterization of a structure-specific resolving enzyme from sulfolobus islandicus rod-shaped virus 2. | sulfolobus islandicus rod shaped virus 2 (sirv2) infects the archaeon sulfolobus islandicus at extreme temperature (70°c-80°c) and acidity (ph 3). sirv2 encodes a holliday junction resolving enzyme (sirv2 hjr) that has been proposed as a key enzyme in sirv2 genome replication. the molecular mechanism for sirv2 hjr four-way junction cleavage bias, minimal requirements for four-way junction cleavage, and substrate specificity were determined. sirv2 hjr cleaves four-way dna junctions with a prefere ... | 2011 | 21858199 |
| simple and elegant design of a virion egress structure in archaea. | some viruses of archaea use an unusual egress mechanism that involves the formation of virus-associated pyramids (vaps) on the host cell surface. at the end of the infection cycle, these structures open outward and create apertures through which mature virions escape from the cell. here we describe in detail the structure and composition of vaps formed by the sulfolobus islandicus rod-shaped virus 2 (sirv2) in cells of its hyperthermophilic archaeal host. we show that the vaps are stable and aut ... | 2011 | 21282609 |
| characterization of sulfolobus islandicus rod-shaped virus 2 gp19, a single-strand specific endonuclease. | the hyperthermophilic sulfolobus islandicus rod-shaped virus 2 (sirv2) encodes a 25-kda protein (sirv2gp19) annotated as a hypothetical protein with sequence homology to the recb nuclease superfamily. even though sirv2gp19 homologs are conserved throughout the rudivirus family and presumably play a role in the viral life cycle, sirv2gp19 has not been functionally characterized. to define the minimal requirements for activity, sirv2gp19 was purified and tested under varying conditions. sirv2gp19 ... | 2011 | 21667093 |
| exploitation of plant and archaeal viruses in bionanotechnology. | cpmv (cowpea mosaic virus), a plant virus, is a naturally occurring sphere-like nanoparticle, and is used as a synthon and/or template in bionanoscience. the virions formed by cpmv can be regarded as programmable nanobuilding blocks with a diameter of approximately 30 nm. a range of molecules have been attached to this viral nanoscaffold, yielding stable nanoparticles that display multiple copies of the desired molecule. it has been shown that, in addition to surface amine groups, surface carbox ... | 2009 | 19614572 |
| unveiling cell surface and type iv secretion proteins responsible for archaeal rudivirus entry. | sulfolobus mutants resistant to archaeal lytic virus sulfolobus islandicus rod-shaped virus 2 (sirv2) were isolated, and mutations were identified in two gene clusters, cluster sso3138 to sso3141 and cluster sso2386 and sso2387, encoding cell surface and type iv secretion proteins, respectively. the involvement of the mutations in the resistance was confirmed by genetic complementation. blocking of virus entry into the mutants was demonstrated by the lack of early gene transcription, strongly su ... | 2014 | 24965447 |
| massive activation of archaeal defense genes during viral infection. | archaeal viruses display unusually high genetic and morphological diversity. studies of these viruses proved to be instrumental for the expansion of knowledge on viral diversity and evolution. the sulfolobus islandicus rod-shaped virus 2 (sirv2) is a model to study virus-host interactions in archaea. it is a lytic virus that exploits a unique egress mechanism based on the formation of remarkable pyramidal structures on the host cell envelope. using whole-transcriptome sequencing, we present here ... | 2013 | 23698312 |
| protein-protein interactions leading to recruitment of the host dna sliding clamp by the hyperthermophilic sulfolobus islandicus rod-shaped virus 2. | viruses infecting hyperthermophilic archaea typically do not encode dna polymerases, raising questions regarding their genome replication. here, using a yeast two-hybrid approach, we have assessed interactions between proteins of sulfolobus islandicus rod-shaped virus 2 (sirv2) and the host-encoded proliferating cell nuclear antigen (pcna), a key dna replication protein in archaea. five sirv2 proteins were found to interact with pcna, providing insights into the recruitment of host replisome for ... | 2014 | 24696494 |
| a unique virus release mechanism in the archaea. | little is known about the infection cycles of viruses infecting cells from archaea, the third domain of life. here, we demonstrate that the virions of the archaeal sulfolobus islandicus rod-shaped virus 2 (sirv2) are released from the host cell through a mechanism, involving the formation of specific cellular structures. large pyramidal virus-induced protrusions transect the cell envelope at several positions, rupturing the s-layer; they eventually open out, thus creating large apertures through ... | 2009 | 19549825 |