Heterologous expression and biochemical characterization of recombinant alpha phosphoglucomutase from Mycobacterium tuberculosis H37Rv

Phosphoglucomutase (PGM) plays an important role in polysaccharide capsule formation and virulence in a number of bacterial pathogens. However, the enzyme has not yet been characterized from Mycobacterium tuberculosis (Mtb). Here, we report the biochemical properties of recombinant Mtb-PGM as well as the in silico structural analysis from Mtb H37Rv. The purified recombinant enzyme was enzymatically active with a specific activity of 67.5 U/mg and experimental kcat of 70.31 s−1 for the substrate glucose-1-phosphate. The enzyme was stable in pH range 6.5–7.4 and exhibited temperature optima range between 30 and 40 °C. Various kinetic parameters and constants of the rPGM were determined. A structural comparison of Modeller generated 3D Mtb-PGM structure with rabbit muscle PGM revealed that the two enzymes share the same overall heart shape and four-domain architecture, despite having only 17% sequence identity. However, certain interesting differences between the two have been identified, which provide an opportunity for designing new drugs to specifically target the Mtb-PGM. Also, in the absence of the crystal structure of the Mtb-PGM, the modeled structure could be further explored for in silico docking studies with suitable inhibitors.

► Recombinant mycobacterial phosphoglucomutase (Mtb PGM) overexpressed and purified and refolded.
► Functional and biochemical characterization of the recombinant PGM performed.
► Structural studies using homology modeled structure of the Mtb PGM conducted.
► Structural differences between the rabbit PGM and the modeled Mtb PGM elucidated.