Essential virulence factor that promotes mycobacterial survival within host macrophages (PubMed:14617138, PubMed:16256440, PubMed:20167798, PubMed:29888212). Acts as a phosphatase that possesses triple substrate specificity toward phosphotyrosine, phosphoserine/threonine and phosphoinositides (PubMed:10986245, PubMed:16271885, PubMed:17584180). Supports mycobacteria survival during infection by modulating the normal host signaling pathways, attenuating the bactericidal immune responses and promoting the host cell survival (PubMed:20167798, PubMed:29888212). Inhibits host inflammatory responses and apoptosis through impeding the NF-kappaB and MAPK signal pathways and TP53/p53 expression in the macrophage (PubMed:29888212). Blocks the IL6/IL-6 production by down-regulating ERK1/2, p38 and p65 activity (PubMed:20167798, PubMed:29888212). Prevents macrophage cell death by activating the Akt pathway and blocking caspase 3 activity (PubMed:20167798, PubMed:29888212). Reduces the expression of iNOS in activated macrophages and inhibits the generation of destroying reactive nitrogen intermediate NO (PubMed:29888212). H2O + O-phospho-L-tyrosyl-[protein] = L-tyrosyl-[protein] + phosphate H2O + O-phospho-L-seryl-[protein] = L-seryl-[protein] + phosphate H2O + O-phospho-L-threonyl-[protein] = L-threonyl-[protein] + phosphate 1,2-dioctanoyl-sn-glycero-3-phospho-(1-D-myo-inositol-3-phosphate) + H2O = 1,2-dioctanoyl-sn-glycero-3-phospho-(1D-myo-inositol) + phosphate 1,2-dioctanoyl-sn-glycero-3-phospho-(1-D-myo-inositol-4-phosphate) + H2O = 1,2-dioctanoyl-sn-glycero-3-phospho-(1D-myo-inositol) + phosphate 1,2-dioctanoyl-sn-glycero-3-phospho-(1D-myo-inositol-5-phosphate) + H2O = 1,2-dioctanoyl-sn-glycero-3-phospho-(1D-myo-inositol) + phosphate Phosphatase activity is inhibited by sodium orthovanadate, a specific inhibitor of tyrosine phosphatases, but not by okadaic acid, an inhibitor of serine/threonine phosphatases (PubMed:10986245). Inhibition of the enzyme reduces mycobacterial survival in infected macrophages (PubMed:19240079, PubMed:20167798, PubMed:21116447, PubMed:30153005). Inhibitors also enhance killing efficacy by first-line antibiotics (PubMed:30153005). kcat is 60.0 sec(-1) with P-Tyr as substrate. kcat is 18.32 sec(-1) with P-Ser as substrate. kcat is 12.5 sec(-1) with P-Thr as substrate. kcat is 159.57 sec(-1) with P-Tyr insulin as substrate. kcat is 158.31 sec(-1) with P-Tyr EGFR as substrate. kcat is 18.08 sec(-1) with P-Ser peptide as substrate. kcat is 9.12 sec(-1) with P-Thr peptide as substrate. kcat is 60.97 sec(-1) with 5'AMP as substrate. kcat is 88.40 sec(-1) with 5'IMP as substrate. kcat is 134.70 sec(-1) with pNPP as substrate. kcat is 38.5 sec(-1) with PtdIns3P as substrate. kcat is 100.3 sec(-1) with PtdIns4P as substrate. kcat is 80.5 sec(-1) with PtdIns5P as substrate. Optimum pH is near 5.5. Further investigation is required to determine whether PtpB is direct substrate for SecA2, the ESX/type VII secretion system, or an alternate mechanism. Adopts a simplified PTP fold, which combines features of the conventional PTPs and dual-specificity phosphatases (PubMed:16271885). In the presence of OMTS inhibitor, the enzyme undergoes a large conformational change, allowing the inhibitor to bind deep in the active-site pocket (PubMed:17437721). Disruption of the gene impairs the ability of the mutant strain to survive in activated murine macrophages and in guinea pigs, but not in resting murine macrophages (PubMed:14617138, PubMed:16256440). Infection of guinea pigs with the mutant strain results in a 70-fold reduction in the bacillary load of spleens in infected animals (PubMed:14617138, PubMed:16256440). Disruption of the gene has no significant effect on the morphology and growth of the mutant in defined liquid culture medium (PubMed:14617138). The important role played by PtpB in virulence and the lack of PtpB human orthologs make it a highly promising target for the treatment of tuberculosis infections. Several classes of potent inhibitors have been developed and studied to date. Drug candidates include, among others, (oxalylamino-methylene)-thiophene sulfonamide (OMTS), isoxazole-based compounds, highly substituted indolo[2,3-a]quinolizidines, benzofuran salicylic acid derivatives, chalcone derivatives and several 2-oxo-1,2-dihydrobenzo[cd]indole-6-sulfonamide and piperazinyl-thiophenyl-ethyl-oxalamide derivatives. Belongs to the protein-tyrosine phosphatase family.