XthA phospholipase contributes the cell-wall functionality of pathogenic mycobacteria by increasing the synthesis of...

The mycobacterial cell wall is a complex structure that plays a critical role in resisting external environmental stress and contributing to pathogenesis, with mycolic acid being a key component in maintaining cell wall integrity. Moreover, the enzymes involved in cell wall synthesis are frequently targeted in antimycobacterial drug research. In this study, we demonstrate that the conserved extracellular DNase XthA from mycobacteria exhibits phospholipase A₁ (PLA₁) activity, whereas this activity is absent in non-pathogenic mycobacteria. Moreover, XthA PLA₁ activity facilitates the formation of cord-like structures, promotes the proliferation of mycobacteria, and enhances their resistance to environmental stressors. Results from ethidium bromide and minimum inhibitory concentration assays suggest that XthA PLA₁ activity reduces the permeability of the mycobacterial cell wall. Furthermore, analyses using scanning electron microscopy and mass spectrometry demonstrated that PLA₁ activity contributes to cell wall integrity and enhances the synthesis of mycolic acids. Additionally, qPCR analysis indicated that XthA PLA₁ activity upregulates the transcript of key genes involved in the MAs synthesis pathway. Collectively, these findings suggest that pathogenic mycobacteria utilize XthA PLA₁ to facilitate cell wall functionality by regulating mycolic acid synthesis, thereby underscoring its potential as a drug target for disrupting the cell wall of pathogenic mycobacteria.