biostudies-literatureDegen DHoward Hughes Medical InstituteNIAID NIH HHSNational Institutes of HealthNIGMS NIH HHSe02451https://www.ebi.ac.uk/biostudies/studies/S-EPMC4029172biostudies-literatureUnknown3We report that bacterial RNA polymerase (RNAP) is the functional cellular target of the depsipeptide antibiotic salinamide A (Sal), and we report that Sal inhibits RNAP through a novel binding site and mechanism. We show that Sal inhibits RNA synthesis in cells and that mutations that confer Sal-resistance map to RNAP genes. We show that Sal interacts with the RNAP active-center 'bridge-helix cap' comprising the 'bridge-helix N-terminal hinge', 'F-loop', and 'link region'. We show that Sal inhibits nucleotide addition in transcription initiation and elongation. We present a crystal structure that defines interactions between Sal and RNAP and effects of Sal on RNAP conformation. We propose that Sal functions by binding to the RNAP bridge-helix cap and preventing conformational changes of theLifeTranscription inhibition by the depsipeptide antibiotic salinamide A.PMC4029172GM084350R01 AI104660P41 GM111244GM041376P41 GM103485R01 GM084350R01 GM041376R01 AI072766AI072766R37 GM041376AI104660Fenical WFeng YTalaue MEbright KYGigliotti MDegen DMandal SEbright RHZhang YConnell NVahedian-Movahed HArnold EEbright YWfalseTranscription inhibition by the depsipeptide antibiotic salinamide A.We report that bacterial RNA polymerase (RNAP) is the functional cellular target of the depsipeptide antibiotic salinamide A (Sal), and we report that Sal inhibits RNAP through a novel binding site and mechanism. We show that Sal inhibits RNA synthesis in cells and that mutations that confer Sal-resistance map to RNAP genes. We show that Sal interacts with the RNAP active-center 'bridge-helix cap' comprising the 'bridge-helix N-terminal hinge', 'F-loop', and 'link region'. We show that Sal inhibits nucleotide addition in transcription initiation and elongation. We present a crystal structure that defines interactions between Sal and RNAP and effects of Sal on RNAP conformation. We propose that Sal functions by binding to the RNAP bridge-helix cap and preventing conformational changes of th2014-01-01T00:00:00Z2014 Apr2026-05-01T23:14:22.947Z2019-03-27T00:14:29ZS-EPMC40291722484300110.7554/eLife.02451