The antibiotic sorangicin A inhibits promoter DNA unwinding in a Mycobacterium tuberculosis rifampicin-resistant RNA polymerase.Lilic, M., Chen, J., Boyaci, H., Braffman, N., Hubin, E.A., Herrmann, J., Muller, R., Mooney, R., Landick, R., Darst, S.A., Campbell, E.A.
(2020) Proc Natl Acad Sci U S A 117: 30423-30432
- PubMed: 33199626
- DOI: 10.1073/pnas.2013706117
- Primary Citation of Related Structures:
6VW0, 6VVS, 6VVT, 6VVV, 6VVY, 6VVX, 6VVZ
- PubMed Abstract:
Rifampicin (Rif) is a first-line therapeutic used to treat the infectious disease tuberculosis (TB), which is caused by the pathogen Mycobacterium tuberculosis ( Mtb ). The emergence of Rif-resistant (Rif R ) Mtb presents a need for new antibiotics ...
Rifampicin (Rif) is a first-line therapeutic used to treat the infectious disease tuberculosis (TB), which is caused by the pathogen Mycobacterium tuberculosis ( Mtb ). The emergence of Rif-resistant (Rif R ) Mtb presents a need for new antibiotics. Rif targets the enzyme RNA polymerase (RNAP). Sorangicin A (Sor) is an unrelated inhibitor that binds in the Rif-binding pocket of RNAP. Sor inhibits a subset of Rif R RNAPs, including the most prevalent clinical Rif R RNAP substitution found in Mtb infected patients (S456>L of the β subunit). Here, we present structural and biochemical data demonstrating that Sor inhibits the wild-type Mtb RNAP by a similar mechanism as Rif: by preventing the translocation of very short RNAs. By contrast, Sor inhibits the Rif R S456L enzyme at an earlier step, preventing the transition of a partially unwound promoter DNA intermediate to the fully opened DNA and blocking the template-strand DNA from reaching the active site in the RNAP catalytic center. By defining template-strand blocking as a mechanism for inhibition, we provide a mechanistic drug target in RNAP. Our finding that Sor inhibits the wild-type and mutant RNAPs through different mechanisms prompts future considerations for designing antibiotics against resistant targets. Also, we show that Sor has a better pharmacokinetic profile than Rif, making it a suitable starting molecule to design drugs to be used for the treatment of TB patients with comorbidities who require multiple medications.
Laboratory of Molecular Biophysics, The Rockefeller University, New York, NY 10065; email@example.com.