title: Virology. A virus that infects a hyperthermophile encapsidates A-form DNA.
abstract: 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 previously unknown form of virion organization. Although almost half of the capsid protein is unstructured in solution, this unstructured region folds in the virion into a single extended α helix that wraps around the DNA. The DNA is entirely in the A-form, which suggests a common mechanism with bacterial spores for protecting DNA in the most adverse environments.
authors.affiliation: Department of Biochemistry, University of Washington, Seattle, WA 98195, USA.
authors.forename: Frank
authors.initials: F
authors.lastname: DiMaio
authors.affiliation: Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA 22908, USA.
authors.forename: Xiong
authors.initials: X
authors.lastname: Yu
authors.affiliation: Institut Pasteur, Department of Microbiology, 25 rue du Dr. Roux, Paris 75015, France.
authors.forename: Elena
authors.initials: E
authors.lastname: Rensen
authors.affiliation: Institut Pasteur, Department of Microbiology, 25 rue du Dr. Roux, Paris 75015, France.
authors.forename: Mart
authors.initials: M
authors.lastname: Krupovic
authors.affiliation: Institut Pasteur, Department of Microbiology, 25 rue du Dr. Roux, Paris 75015, France. egelman@virginia.edu david.prangishvili@pasteur.fr.
authors.forename: David
authors.initials: D
authors.lastname: Prangishvili
authors.affiliation: Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA 22908, USA. egelman@virginia.edu david.prangishvili@pasteur.fr.
authors.forename: Edward H
authors.initials: EH
authors.lastname: Egelman
mesh_terms: D000595:Amino Acid Sequence; D020285:Cryoelectron Microscopy; D044704:DNA, A-Form / Q000378:metabolism*; D008969:Molecular Sequence Data; D055503:Protein Multimerization; D017433:Protein Structure, Secondary; D023642:Rudiviridae / Q000378:metabolism* / Q000648:ultrastructure; D013171:Spores, Bacterial / Q000235:genetics / Q000821:virology; D016944:Sulfolobus / Q000235:genetics* / Q000821:virology*; D014771:Virion / Q000648:ultrastructure*
chemical_list: D044704:DNA, A-Form