Subgroups of tuberculosis-causing bacteria can persist even when antibiotics wipe out most of the population. The need to eliminate these persistent subpopulations is one reason why TB treatment regimens are so lengthy. Now, NIAID-supported researchers have shown that a single protein allows mycobacteria to generate diverse populations that can avoid TB drugs. The protein may be a target for intervention; blocking it might result in less mycobacterial diversity and shorten TB treatment courses.