Phosphorylation of Mycobacterium tuberculosis Ser/Thr Phosphatase by PknA and PknB
Figure 1
(A) Schematic representation of PstP with critical residues (Arg20, Asp38 and Asp229) being highlighted with upward arrows. (B) Activity profiles of PstPc and its mutants: Activity assays were performed by pNPP-hydrolysis mediated by PstPc, PstPcR20G, PstPcD38G and PstPcD229G. Increasing concentrations of proteins were taken with constant substrate concentration (10 mM pNPP) and incubated at 37°C for 30 mins. As shown in the graph, the mutants had lost phosphatase activity to different extents. Activity is calculated as a measure of µmoles of pNPP hydrolyzed per min. at a given enzyme concentration. (C) The relative activity of all the phosphatase variants (5 µg each, 30 min.) showed that PstPcD38G and PstPcD229G had lost >90% of activity while PstPcR20G lost ∼60% of the activity as compared to PstPc. The error bars indicate the SD of three individual experiments.