The Rockefeller University, New York, United States.
Department of Biochemistry, University of Wisconsin-Madison, Madison, United States.
Elife. 2018 Feb 26;7:e34823. doi: 10.7554/eLife.34823.
Fidaxomicin (Fdx) is an antimicrobial RNA polymerase (RNAP) inhibitor highly effective against RNAP in vitro, but clinical use of Fdx is limited to treating 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 RNAP holoenzyme in complex with Fdx. We find that the actinobacteria general transcription factor RbpA contacts fidaxomycin, explaining its strong effect on . Additional structures define conformational states of 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.
非达霉素（Fdx）是一种抗微生物 RNA 聚合酶（RNAP）抑制剂，在体外对 RNAP 具有高度的有效性，但由于吸收不良，Fdx 的临床应用仅限于治疗肠道感染。为了确定 Fdx 与 RNAP 结合的结构决定因素，我们确定了与 Fdx 复合的完整 RNAP 全酶的 3.4 Å 冷冻电子显微镜结构。我们发现放线菌一般转录因子 RbpA 与 fidaxomycin 接触，解释了它对 RNAP 的强烈影响。其他结构定义了游离 apo-全酶和启动子结合的开放复合物之间的 RNAP 构象状态，以便进行转录。结果表明，Fdx 像一个门挡一样，将酶卡在开放状态，阻止了将启动子 DNA 固定在活性位点所必需的运动。我们的结果提供了一个结构平台，可指导基于 Fdx 结合口袋的抗结核抗菌药物的开发。
