Functional Characterization of MIP_07528 of for Tyrosine Phosphatase Activity Displays Sensitivity to Oxidative Inactivation and Plays a Role in Immunomodulation.

(MIP), an atypical mycobacterium originally developed as an anti-leprosy vaccine, has emerged as a potent immunomodulator with diverse therapeutic applications. Despite its clinical significance, molecular mechanisms underlying MIP's immunomodulatory properties remain largely unexplored. Bacterial phosphatases are recognized as crucial virulence factors that enable pathogens to evade host defenses by modulating host immune signaling pathways, including phosphoinositide metabolism. MIP_07528 was identified as a putative protein tyrosine phosphatase B (PtpB) ortholog through in silico analysis, with significant sequence conservation observed within catalytic domains of pathogenic mycobacterial PtpB proteins. Phosphatase activity was detected in both cell lysate and culture filtrate fractions, revealing differential expression patterns between MIP and . Upregulation of MIP_07528 was demonstrated under oxidative stress, suggesting involvement in stress adaptation. The recombinant protein exhibited distinctive kinetic properties, characterized by higher substrate affinity yet increased susceptibility to oxidative inactivation compared to its M. tuberculosis counterpart. In macrophages, MIP_07528 suppressed pro-inflammatory cytokines while enhancing anti-inflammatory IL-10 production. These findings establish MIP_07528 as a functional phosphatase that may contribute to MIP's immunomodulatory properties. This work advances understanding of phosphatase function in non-pathogenic mycobacteria while providing insights into virulence factor evolution and establishing a foundation for novel antimicrobial strategies.