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Updated: May 30, 2026

Probing mRNA Kinetics in Space and Time in Escherichia coli using Two-Color Single-Molecule Fluorescence In Situ Hybridization
Published on: July 30, 2020
Spatial distribution and diffusive motion of RNA polymerase in live Escherichia coli
Benjamin P Bratton1, Rachel A Mooney, James C Weisshaar
1Department of Chemistry, University of Wisconsin-Madison, 1101 University Ave., Madison, WI 53706, USA.
Abstract:
By labeling the β' subunit of RNA polymerase (RNAP), we used fluorescence microscopy to study the spatial distribution and diffusive motion of RNAP in live Escherichia coli cells for the first time. With a 40-ms time resolution, the spatial distribution exhibits two or three narrow peaks of 300- to 600-nm full width at half-maximum that maintain their positions within 60 nm over 1 s. The intensity in these features is 20 to 30% of the total. Fluorescence recovery after photobleaching (FRAP) measures the diffusive motion of RNAP on the 1-μm length scale. Averaged over many cells, 53%±19% of the RNAP molecules were mobile on the 3-s timescale, with a mean apparent diffusion constant
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