Purification and functional characterization of diadenosine 5′,5‴-P1,P4-tetraphosphate phosphorylases from Mycobacterium smegmatis and Mycobacterium avium

We recently demonstrated that the Rv2613c protein from Mycobacterium tuberculosis H37Rv is a novel diadenosine 5′,5‴-P1,P4-tetraphosphate (Ap4A) phosphorylase (MtAPA) that forms a tetramer. Mycobacterium avium and Mycobacterium smegmatis express proteins named MAV_3489 and MSMEG_2932, respectively, that are homologous to MtAPA. Here we showed that the MAV_3489 and MSMEG_2932 proteins possess Ap4A phosphorylase activity and enzymatic properties similar to those of MtAPA. Furthermore, gel-filtration column chromatography revealed that MAV_3489 and MSMEG_2932 assembled into homotetramers in solution, indicating that they may also form unique Ap4A-binding sites composed of tetramers.