Fidaxomicin jams Mycobacterium tuberculosis RNA polymerase motions needed for initiation via RbpA contacts
- The Rockefeller University, United States
- University of Wisconsin-Madison, United States
Abstract
Fidaxomicin (Fdx) is an antimicrobial RNA polymerase (RNAP) inhibitor highly effective against Mycobacterium tuberculosis RNAP in vitro, but clinical use of Fdx is limited to treating Clostridium difficile intestinal infections due to poor absorption. To identify the structural determinants of Fdx binding to RNAP, we determined the 3.4 Å cryo-electron microscopy structure of a complete M. tuberculosis RNAP holoenzyme in complex with Fdx. We find that the actinobacteria general transcription factor RbpA contacts fidaxomycin, explaining its strong effect on M. tuberculosis. Additional structures define conformational states of M. tuberculosis RNAP between the free apo-holoenzyme and the promoter-engaged open complex ready for transcription. The results establish that Fdx acts like a doorstop to jam the enzyme in an open state, preventing the motions necessary to secure promoter DNA in the active site. Our results provide a structural platform to guide development of anti-tuberculosis antimicrobials based on the Fdx binding pocket.
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Funding
The Rockefeller University (Women in Science Fellowship)
- Hande Boyaci
National Institute of General Medical Sciences (R01 GM38660)
- Robert Landick
National Institute of General Medical Sciences (R35 GM118130)
- Seth A Darst
National Institute of General Medical Sciences (R01 GM114450)
- Elizabeth A Campbell
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2018, Boyaci et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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Fidaxomicin jams Mycobacterium tuberculosis RNA polymerase motions needed for initiation via RbpA contacts
eLife 7:e34823.
https://doi.org/10.7554/eLife.34823
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