Inhibition of Bacterial Gene Transcription with an RpoN-Based Stapled Peptide.

In response to environmental and other stresses, the σ subunit of bacterial RNA polymerase (RNAP) controls expression of several genes that play a significant role in the virulence of both plant and animal pathogens. Recruitment of σ to RNAP initiates promoter-specific transcription via the double-stranded DNA denaturation mechanism of the cofactor. The RpoN box, a recognition helix found in the C-terminal region of σ, has been identified as the component necessary for major groove insertion at the -24 position of the promoter. We employed the hydrocarbon stapled peptide methodology to design and synthesize stapled σ peptides capable of penetrating Gram-negative bacteria, binding the σ promoter, and blocking the interaction between endogenous σ and its target DNA sequence, thereby reducing transcription and activation of σ response genes.