Recombinant portal protein from Staphylococcus epidermidis bacteriophage CNPH82 is a 13-subunit oligomer

The portal protein cn3 of bacteriophage CNPH82 is predicted to serve as a gateway for translocation of viral genome into preformed pro‐capsid, like portal proteins from other double‐stranded DNA tailed bacteriophages. The host of bacteriophage CNPH82 is the opportunistic human pathogenic bacterium Staphylococcus epidermidis, a major cause of nosocomial infections. The portal protein of this phage has been cloned, overexpressed and purified. Size‐exclusion chromatography–multi‐angle laser light scattering analysis has indicated that the portal protein contains ∼13 subunits. Crystals of the portal protein, diffracting to 4.2 Å, have been obtained. These crystals belong to the space group C2221 with the unit‐cell parameters of a = 252.4, b = 367.0, c = 175.5 Å. The self‐rotation function revealed the presence of a single 13‐subunit oligomer in the asymmetric unit.