New structure solved for hyperthermophilic DNA virus

A new Science paper is out from IPD faculty Dr. Frank DiMaio titled A virus that infects a hyperthermophile encapsidates A-form DNA. Read the abstract below and the article at the link: http://www.sciencemag.org/content/348/6237/914.full.pdf

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 a 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.

DiMaio_virusAform_2015
The SIRV2 protein dimer helices fully encapsulate the DNA. (A) Three asymmetric units of the virion are shown, illustrating how the N-terminal helices wrap around the DNA, forming antiparallel helix-helix packing. (B) Side view. (C) Surface view of the protein (using a 1.4 Å probe radius). (D) The right-handed solenoidal supercoiling of the DNA, with three turns shown.