Endy: Journal Club: Le et al 2005

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Reference

Proc Natl Acad Sci U S A. 2005 Jun 28;102(26):9160-4. Epub 2005 Jun 20.

Real-time RNA profiling within a single bacterium.

Le TT, Harlepp S, Guet CC, Dittmar K, Emonet T, Pan T, Cluzel P.

Institute for Biophysical Dynamics and The James Franck Institute and Department of Biochemistry and Molecular Biology, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637, USA.

Characterizing the dynamics of specific RNA levels requires real-time RNA profiling in a single cell. We show that the combination of a synthetic modular genetic system with fluorescence correlation spectroscopy allows us to directly measure in real time the activity of any specific promoter in prokaryotes. Using a simple inducible gene expression system, we found that induced RNA levels within a single bacterium of Escherichia coli exhibited a pulsating profile in response to a steady input of inducer. The genetic deletion of an efflux pump system, a key determinant of antibiotic resistance, altered the pulsating transcriptional dynamics and caused overexpression of induced RNA. In contrast with population measurements, real-time RNA profiling permits identifying relationships between genotypes and transcriptional dynamics that are accessible only at the level of the single cell.