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 C222， 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.