Structural highlights
FunctionRPOZ_ECOLI Promotes RNA polymerase assembly. Latches the N- and C-terminal regions of the beta' subunit thereby facilitating its interaction with the beta and alpha subunits.[HAMAP-Rule:MF_00366] Publication Abstract from PubMedThe nucleotide-addition cycle (NAC) of multi-subunit DNA-dependent RNA polymerases (RNAPs) involves coordinated conformational changes in conserved active-site structural elements, including the trigger loop (TL). The TL is open (unfolded) in most RNAP structures but can close (fold) in substrate-bound (post- or pre-translocated) states of the RNAP, promoting catalysis. TL closure has been associated with closure of another conserved structural element, the Rim-Helices/F-loop (RH-FL), but the role of the RH-FL in the NAC is unclear. Antibiotic leads CBR9379 and AAP-SO (2) inhibit the Escherichia coli and Mycobacterium tuberculosis RNAPs, respectively, by binding in a pocket formed by the bridge helix and RH-FL. The precise mechanism of action for these inhibitors is yet to be defined. We present cryo-electron microscopy structures showing that both compounds inhibit the RNAP NAC by preventing RH-FL closure, thereby allosterically destabilizing the closed TL. This work reveals a conserved mechanistic principle of RNAP catalysis across all domains of life and provides new insight for antibiotic design. RNA polymerase inhibitors reveal active-site motions essential for the nucleotide-addition cycle.,Dhingra Y, Landick R, Campbell EA, Darst SA bioRxiv [Preprint]. 2026 Apr 7:2026.04.06.716786. doi: , 10.64898/2026.04.06.716786. PMID:41993335[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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