Antibacterial Peptide Microcin J25 Inhibits Transcription by Binding within and Obstructing the RNA Polymerase Secondary Channel

Abstract

The antibacterial peptide microcin J25 (MccJ25) inhibits transcription by bacterial RNA polymerase (RNAP). Biochemical results indicate that inhibition of transcription occurs at the level of NTP uptake or NTP binding by RNAP. Genetic results indicate that inhibition of transcription requires an extensive determinant, comprising more than 50 amino acid residues, within the RNAP secondary channel (also known as the "NTP-uptake channel" or "pore"). Biophysical results indicate that inhibition of transcription involves binding of MccJ25 within the RNAP secondary channel. Molecular modeling indicates that binding of MccJ25 within the RNAP secondary channel obstructs the RNAP secondary channel. We conclude that MccJ25 inhibits transcription by binding within and obstructing the RNAP secondary channel--acting essentially as a "cork in a bottle." Obstruction of the RNAP secondary channel represents an attractive target for drug discovery.

Deciphering the tRNA-dependent lipid aminoacylation systems in bacteria: Novel components and structural advances

“…7 Beyond direct interaction with membrane components, certain CAMPs pass through the cytoplasmic membrane to inhibit intracellular targets. For instance, the bacterial peptide microcin J25 (MccJ25) inhibits RNA polymerase, 8 while apidaecins (in honeybees), oncocins (in insects), and Bactenecin-7 (in mammalian cells) inhibit bacterial translation by binding to ribosomal proteins. 9,10 …”

Topoisomer Differentiation of Molecular Knots by FTICR MS: Lessons from Class II Lasso Peptides

“…Microcin J25 (MccJ25) is a lasso peptide secreted by Escherichia coli AY25 that exerts potent antibacterial activity against Escherichia and Salmonella species, through import in the target bacteria upon interaction with the ironsiderophore receptor FhuA [13] and inhibition of the RNA polymerase [14]. Its C-terminal (18-21 SFYG) segment is sterically entrapped into the macrolactam ring by F19 and Y20 located on each side of the ring.…”

The iron–siderophore transporter FhuA is the receptor for the antimicrobial peptide microcin J25: role of the microcin Val11–Pro16 β-hairpin region in the recognition mechanism

“…Indeed, MccJ25 was shown to inhibit transcription by targeting the β subunit of RNA polymerase [6,7]. The molecular mechanism involves MccJ25 binding and obstruction of the RNA polymerase secondary channel, which in turn prevents the correct positioning of NTP substrates [8,9]. Conversely, few studies have addressed MccJ25 recognition at bacterial membranes.…”