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DNA viruses of the Archaea have highly diverse and often exceptionally complex morphotypes. Many have been isolated from geothermally heated hot environments, raising intriguing questions about their origins, and contradicting the widespread notion of limited biodiversity in extreme environments. Here, we provide a unifying view on archaeal viruses, and(More)
This minireview summarizes what is known about genetic elements in the archaeal crenarchaeotal genus Sulfolobus, including recent work on viruses, cryptic plasmids, a novel type of virus satellite plasmids or satellite viruses, and conjugative plasmids (CPs), mostly from our laboratory. It does not discuss IS elements and transposons.
The unenveloped, stiff-rod-shaped, linear double-stranded DNA viruses SIRV1 and SIRV2 from Icelandic Sulfolobus isolates form a novel virus family, the Rudiviridae. The sizes of the genomes are 32. 3 kbp for SIRV1 and 35.8 kbp for SIRV2. The virions consist of a tube-like superhelix formed by the DNA and a single basic 15.8-kD DNA-binding protein. The tube(More)
This review summarizes the electron microscopical descriptions of prokaryote viruses. Since 1959, nearly 6300 prokaryote viruses have been described morphologically, including 6196 bacterial and 88 archaeal viruses. As in previous counts, the vast majority (96.3 %) are tailed, and only 230 (3.7 %) are polyhedral, filamentous, or pleomorphic. The family(More)
In terms of virion morphology, the known viruses of archaea fall into two distinct classes: viruses of mesophilic and moderately thermophilic Eueryarchaeota closely resemble head-and-tail bacteriophages whereas viruses of hyperthermophilic Crenarchaeota show a variety of unique morphotypes. In accord with this distinction, the sequenced genomes of(More)
A new Sulfolobus islandicus strain, REY15/4, harboured both a novel fusellovirus, SSV2, and a small plasmid, pSSVx. The plasmid spread in S. solfataricus P1 together with the virus after infection with either the supernatant of a culture of REY15/4 or purified virus. Spreading of the plasmid required co-transfection with either SSV2 or the related SSV1 as(More)
Compartmentalization is an important organizational feature of life. It occurs at varying levels of complexity ranging from eukaryotic organelles and the bacterial microcompartments, to the molecular reaction chambers formed by enzyme assemblies. The structural basis of enzyme encapsulation in molecular compartments is poorly understood. Here we show, using(More)
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(More)
Prokaryotes, bacteria and archaea, are the most abundant cellular organisms among those sharing the planet Earth with human beings (among others). However, numerous ecological studies have revealed that it is actually prokaryotic viruses that predominate on our planet and outnumber their hosts by at least an order of magnitude. An understanding of how this(More)