6r9b | pdb_00006r9b
Cryo-EM structure of bacterial RNAP with a DNA mimic protein Ocr from T7 phage
Structural highlights
FunctionRPOA_ECOLI DNA-dependent RNA polymerase catalyzes the transcription of DNA into RNA using the four ribonucleoside triphosphates as substrates. This subunit plays an important role in subunit assembly since its dimerization is the first step in the sequential assembly of subunits to form the holoenzyme.[HAMAP-Rule:MF_00059] Publication Abstract from PubMedBacteriophage T7 infects Escherichia coli and evades the host restriction/modification system. The Ocr protein of T7 was shown to exist as a dimer mimicking DNA and to bind to host restriction enzymes, thus preventing the degradation of the viral genome by the host. Here we report that Ocr can also inhibit host transcription by directly binding to bacterial RNA polymerase (RNAP) and competing with the recruitment of RNAP by sigma factors. Using cryo electron microscopy, we determined the structures of Ocr bound to RNAP. The structures show that an Ocr dimer binds to RNAP in the cleft, where key regions of sigma bind and where DNA resides during transcription synthesis, thus providing a structural basis for the transcription inhibition. Our results reveal the versatility of Ocr in interfering with host systems and suggest possible strategies that could be exploited in adopting DNA mimicry as a basis for forming novel antibiotics. Structural basis of transcription inhibition by the DNA mimic protein Ocr of bacteriophage T7.,Ye F, Kotta-Loizou I, Jovanovic M, Liu X, Dryden DT, Buck M, Zhang X Elife. 2020 Feb 10;9. pii: 52125. doi: 10.7554/eLife.52125. PMID:32039758[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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