PMID: 26699645
Dellas N, Snyder JC, Dills M, Nicolay SJ, Kerchner KM, Brumfield SK, Lawrence CM, Young MJ
Structure-based mutagenesis of STIV B204 reveals essential residues in the virion-associated DNA packaging ATPase.
J Virol. 2015 Dec 23. pii: JVI.02435-15.
Sulfolobus turreted icosahedral virus (STIV), an archaeal virus that infects the hyperthermoacidophile, Sulfolobus solfataricus, is one of the most well studied viruses of the domain Archaea. STIV shares structural, morphological, and sequence similarities with viruses from other domains of life, all of which are thought to belong to the same viral lineage. Several of these common features include a conserved coat protein fold, an internal lipid membrane, and a DNA-packaging ATPase. B204 is the ATPase encoded by STIV and is thought to drive packaging of viral DNA during the replication process. Here, we report the crystal structure of B204 along with the biochemical analysis of B204 mutants chosen based on structural information and sequence conservation patterns observed among members of the same viral lineage and the larger FtsK/HerA Superfamily to which B204 belongs. Both in vitro ATPase activity assays and transfection assays with mutant forms of B204 confirmed the essentiality of conserved and non-conserved positions. We have also identified two distinct particle morphologies during a STIV infection that differ in their presence of the B204 protein. The biochemical and structural data presented herein is informative for not only the STIV replication process, but can also be useful in deciphering DNA-packaging mechanisms for other viruses belonging to this lineage. IMPORTANCE: Sulfolobus turreted icosahedral virus (STIV) is a virus that infects a host from the domain Archaea that replicates in high temperature, acidic environments. While STIV has many unique features, there exist several striking similarities between this virus and others that replicate in different environments and infect a broad range of hosts from Bacteria and Eukarya. Aside from structural features shared by viruses from this lineage, there exists a significant level of sequence similarity between the ATPase genes encoded by these different viruses; this gene encodes an enzyme thought to provide energy that drives DNA-packaging into the virion during infection. The experiments described here highlight the elements of this enzyme that are essential for proper function and also provide supporting evidence that B204 is present in the mature STIV virion.