A packing for A-form DNA in an icosahedral virus

Viruses need to package nucleic acid genomes so that the genetic material (either RNA or DNA) can survive outside of a cell and without the DNA repair that takes place within all cells. We have studied the structure of an icosahedral virus that infects a host living in nearly boiling acid. The outer capsid which covers the genome-containing membrane vesicle is composed of 2 proteins that have a variation of a previously observed fold. The genomic DNA is in the A-form first described for desiccated DNA, rather than the B-form more commonly found in biology. A-DNA may be the prevalent storage form of DNA in everything from bacterial spores to viruses inhabiting the most extreme environments.