X-ray crystal structures of the Escherichia coli RNA polymerase in complex with benzoxazinorifamycins

Vadim Molodtsov, Irosha N. Nawarathne, Nathan T. Scharf, Paul D. Kirchhoff, H. D.Hollis Showalter, George A. Garcia, Katsuhiko S. Murakami

Research output: Contribution to journalArticlepeer-review

48 Scopus citations


Rifampin, a semisynthetic rifamycin, is the cornerstone of current tuberculosis treatment. Among many semisynthetic rifamycins, benzoxazinorifamycins have great potential for TB treatment due to their superior affinity for wild-type and rifampin-resistant Mycobacterium tuberculosis RNA polymerases and their reduced hepatic Cyp450 induction activity. In this study, we have determined the crystal structures of the Escherichia coli RNA polymerase complexes with two benzoxazinorifamycins. The ansa-naphthalene moieties of the benzoxazinorifamycins bind in a deep pocket of the β subunit, blocking the path of the RNA transcript. The C3′-tail of benzoxazinorifamycin fits a cavity between the β subunit and σ factor. We propose that in addition to blocking RNA exit, the benzoxazinorifamycin C3′-tail changes the σ region 3.2 loop position, which influences the template DNA at the active site, thereby reducing the efficiency of transcription initiation. This study supports expansion of structure-activity relationships of benzoxazinorifamycins inhibition of RNA polymerase toward uncovering superior analogues with development potential.

Original languageEnglish (US)
Pages (from-to)4758-4763
Number of pages6
JournalJournal of Medicinal Chemistry
Issue number11
StatePublished - Jun 13 2013

All Science Journal Classification (ASJC) codes

  • Molecular Medicine
  • Drug Discovery


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