Expression, purification and crystallization of phosphoribosyl transferase from a mycobacteriophage

Tuberculosis (TB) continues to remain a leading cause of death globally. Of particular concern is the emergence and rise in incidence of multidrug-resistant and extremely drug-resistant cases of TB. To counter this threat, it is important to explore alternative therapies, including phage therapy. Phage BTCU-1 specifically infects Mycobacterium spp. and kills the majority of them. Intriguingly, many proteins from the phage do not share high amino-acid sequence identity with proteins from species other than phages. Here, the expression, purification and crystallization of one such protein, a putative phosphoribosyl transferase from phage BTCU-1, is reported. The crystals belonged to space group C222₁, with unit-cell parameters a = 59.71, b = 64.42, c = 65.32 Å, α = β = γ = 90°. The crystals diffracted X-rays to 2.2 Å resolution.