6c04
Mtb RNAP Holo/RbpA/double fork DNA -closed clamp
Structural highlights
FunctionRBPA_MYCTU Binds to RNA polymerase (RNAP), stimulating and stabilizing the formation of stable RNAP promoter complexes up to 2-fold from principal sigma factor SigA-dependent but not alternative sigma factor SigF-dependent promoters. Increases the affinity of core RNAP for SigA, increasing the transcriptional activity of RNAP. Unlike the case in M.smegmatis or S.coelicolor, has no effect on rifampicin inhibition of transcription. Has no effect on E.coli RNAP.[1] Publication Abstract from PubMedFidaxomicin (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 A 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. Fidaxomicin jams Mycobacterium tuberculosis RNA polymerase motions needed for initiation via RbpA contacts.,Boyaci H, Chen J, Lilic M, Palka M, Mooney RA, Landick R, Darst SA, Campbell EA Elife. 2018 Feb 26;7. pii: 34823. doi: 10.7554/eLife.34823. PMID:29480804[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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