Real-time visualization reveals Mycobacterium tuberculosis ESAT-6 disrupts phagosome-like compartment via fibril-mediated vesiculation
Debraj Koiri, Mintu Nandi, A. M., Jayesh Bhausaheb Aher, Akhil Kumar, Assirbad Behura, Geetanjali Meher, Vineet Choudhary, Sandeep Choubey, Mohammed Saleem
Abstract
Mycobacterium tuberculosis (Mtb) evades host defense by hijacking and rupturing the phagosome. ESAT-6, a secreted virulence protein of Mtb, is known to be critical for phagosome rupture. However, the mechanism of ESAT-6-mediated disruption of the phagosomal membrane remains unknown. Using in vitro reconstitution, live-cell imaging, and numerical simulations, we discover that ESAT-6 polymerization forces remodeling and vesiculation of the phagosome-like compartment both in vitro and in vivo. Shallow insertion of ESAT-6 leads to tubular and bud-like deformations on the membrane facilitated by a reduction in membrane tension. Growing fibrils generate both radial and tangential forces causing local remodeling and shape transition of the membrane into buds. The ESAT-6-bound tensed membrane undergoes local changes in membrane curvature and lipid phase separation that assist the subsequent fission. Overall, the findings provide mechanistic insights into the long-standing question of phagosome disruption by Mtb for its escape.