title: The putative small terminase from the thermophilic dsDNA bacteriophage G20C is a nine-subunit oligomer.
abstract: The assembly of double-stranded DNA bacteriophages is dependent on a small terminase protein that normally plays two important roles. Firstly, the small terminase protein specifically recognizes viral DNA and recruits the large terminase protein, which makes the initial cut in the dsDNA. Secondly, once the complex of the small terminase, the large terminase and the DNA has docked to the portal protein, and DNA translocation into a preformed empty procapsid has begun, the small terminase modulates the ATPase activity of the large terminase. Here, the putative small terminase protein from the thermostable bacteriophage G20C, which infects the Gram-negative eubacterium Thermus thermophilus, has been produced, purified and crystallized. Size-exclusion chromatography-multi-angle laser light scattering data indicate that the protein forms oligomers containing nine subunits. Crystals diffracting to 2.8 Å resolution have been obtained. These belonged to space group P2₁2₁2₁, with unit-cell parameters a = 94.31, b = 125.6, c = 162.8 Å. The self-rotation function and Matthews coefficient calculations are consistent with the presence of a nine-subunit oligomer in the asymmetric unit.
authors.affiliation: York Structural Biology Laboratory, Department of Chemistry, University of York, York YO10 5DD, England.
authors.forename: Juan
authors.initials: J
authors.lastname: Loredo-Varela
authors.forename: Maria
authors.initials: M
authors.lastname: Chechik
authors.forename: Vladimir M
authors.initials: VM
authors.lastname: Levdikov
authors.forename: Ahmad
authors.initials: A
authors.lastname: Abd-El-Aziz
authors.forename: Leonid
authors.initials: L
authors.lastname: Minakhin
authors.forename: Konstantin
authors.initials: K
authors.lastname: Severinov
authors.forename: Callum
authors.initials: C
authors.lastname: Smits
authors.forename: Alfred A
authors.initials: AA
authors.lastname: Antson
mesh_terms: D001435:Bacteriophages / Q000737:chemistry*; D018360:Crystallography, X-Ray; D004247:DNA / Q000737:chemistry*; D004706:Endodeoxyribonucleases / Q000737:chemistry*; D016963:Thermus thermophilus / Q000821:virology*
chemical_list: D004247:DNA; D004706:Endodeoxyribonucleases; C030894:terminase
keywords: Thermus thermophilus; bacteriophage G20C; putative small terminase
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