Related Experiment Video
Updated: Aug 23, 2026

Synthesis of Masarimycin, a Small Molecule Inhibitor of Gram-Positive Bacterial Growth
Published on: January 7, 2022
Molecular mechanism of transcription inhibition by peptide antibiotic Microcin J25
Karen Adelman1, Julia Yuzenkova, Arthur La Porta
1Department of Molecular Biology and Biochemistry, Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York 14853, USA. ka42@cornell.edu
Abstract:
21 amino acid peptide Microcin J25 (MccJ25) inhibits transcription by bacterial RNA polymerase (RNAP). MccJ25-resistance mutations cluster in the RNAP secondary channel through which incoming NTP substrates are thought to reach the catalytic center and the 3' end of the nascent RNA is likely to thread in backtracked transcription complexes. The secondary channel also accepts transcript cleavage factors GreA and GreB. Here, we demonstrate that MccJ25 inhibits GreA/GreB-dependent transcript cleavage, impedes formation of backtracked complexes, and can be crosslinked to the 3'-end of the nascent RNA in elongation complexes. These results place the MccJ25 binding site within the secondary channel. Moreover, single-molecule assays reveal that MccJ25 binding to a transcribing RNAP temporarily stops transcript elongation but has no effect on the elongation velocity between pauses. Kinetic analysis of single-molecule data allows us to put forward a model of transcription inhibition by MccJ25 that envisions the complete occlusion of the secondary channel by bound inhibitor.
More Related Videos
Related Concept Videos
Eukaryotic Transcription Inhibitors
Eukaryotic transcription inhibitors usually contain two distinct domains, a DNA...
Transcription Attenuation in Prokaryotes
There are several different mechanisms used to attenuate transcription. In ribosome mediated...
Inhibitors of Bacterial Protein Synthesis
Inhibitors of Gram-positive Cell Wall Synthesis
Types of RNA
Three main types of RNA are involved in protein synthesis: messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA). These RNAs perform diverse functions and can be broadly classified as protein-coding or non-coding RNA. Non-coding RNAs play important roles in the regulation of gene expression in response to developmental and environmental changes. Non-coding RNAs in prokaryotes can be manipulated to develop more effective antibacterial drugs for human or animal use.
RNA...
Types of RNA
RNA Performs Diverse...

