FIGURE 1. Fdx is a narrow-spectrum antibiotic inhibiting Cdiff RNA polymerase. Fdx (shown in ball sphere) fits in the narrow gap between β and β' subunit of Cdiff RNAP and jams the RNAP clamp (dash line region) in an open state. The structure is sliced at the level of the Fdx-binding pocket. Note that the Sigma A factor was removed from the structure (PDB: 7L7B) for visualization purposes. Inset, magnification of Fdx sensitizer residue β'K84 interacting with the hydrophilic group of Fdx. Fdx and β'K84 residue are shown in ball-and-stick representations.

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