PMID: 25999507 , Related PDB id: 3J9X
DiMaio F, Yu X, Rensen E, Krupovic M, Prangishvili D, Egelman EH
Virology. A virus that infects a hyperthermophile encapsidates A-form DNA.
Science. 2015 May 22;348(6237):914-7. doi: 10.1126/science.aaa4181.
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 degrees 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 alpha 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.