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

Abstract

In response to environmental and other stresses, the σ⁵⁴ 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 σ⁵⁴ 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 σ⁵⁴, 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 σ⁵⁴ peptides capable of penetrating Gram-negative bacteria, binding the σ⁵⁴ promoter, and blocking the interaction between endogenous σ⁵⁴ and its target DNA sequence, thereby reducing transcription and activation of σ⁵⁴ response genes.

Keywords: DNA-binding proteins; antibiotic resistance; bacterial transcription; cell-penetrating peptides; nitrogen starvation; stapled peptides; σ factor 54.