Malinen Anssi M, Nandymazumdar Monali, Turtola Matti, Malmi Henri, Grocholski Thadee, Artsimovitch Irina, Belogurov Georgiy A
Department of Biochemistry, University of Turku, Turku 20014, Finland.
Department of Microbiology, The Ohio State University, Columbus, Ohio 43210, USA.
Nat Commun. 2014 Mar 6;5:3408. doi: 10.1038/ncomms4408.
Bacterial RNA polymerase (RNAP) is a validated target for antibacterial drugs. CBR703 series antimicrobials allosterically inhibit transcription by binding to a conserved α helix (β' bridge helix, BH) that interconnects the two largest RNAP subunits. Here we show that disruption of the BH-β subunit contacts by amino-acid substitutions invariably results in accelerated catalysis, slowed-down forward translocation and insensitivity to regulatory pauses. CBR703 partially reverses these effects in CBR-resistant RNAPs while inhibiting catalysis and promoting pausing in CBR-sensitive RNAPs. The differential response of variant RNAPs to CBR703 suggests that the inhibitor binds in a cavity walled by the BH, the β' F-loop and the β fork loop. Collectively, our data are consistent with a model in which the β subunit fine tunes RNAP elongation activities by altering the BH conformation, whereas CBRs deregulate transcription by increasing coupling between the BH and the β subunit.
Zotero 插件
