Resuscitation-Promoting Factors Are Required for β-Lactam Tolerance and the Permeability Barrier in Mycobacterium tuberculosis

Mycobacterial resuscitation-promoting factors (RPFs) have been of great interest since the discovery that they promote the growth of nonculturable Mycobacterium tuberculosis cells. Yet, their precise role in mycobacterial survival and infection has remained elusive. We performed a chemical screen to identify molecules that show preferential killing of a Mycobacterium tuberculosis mutant lacking RPFs over wild-type bacilli and found that the mutant has enhanced sensitivity to the beta-lactam class of antibiotics. By monitoring beta-lactam diffusion across the mycobacterial outer membrane, we found that the RPFs are required to maintain the outer membrane integrity, as their deletion results in an increase in outer membrane permeability.