Nucleic Acids Research Advance Access originally published online on May 30, 2008
Nucleic Acids Research 2008 36(12):e73; doi:10.1093/nar/gkn329
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Nucleic Acids Research, 2008, Vol. 36, No. 12 e73
© 2008 The Author(s)
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/2.0/uk/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Methods Online |
Minimally invasive determination of mRNA concentration in single living bacteria
lin C. GuetThe James Franck Institute, Institute for Biophysical Dynamics, Department of Physics, The University of Chicago, 929 E 57th St, Chicago, IL 60637, USA
*To whom correspondence should be addressed. Tel: 773-834-9096; Email: cluzel{at}uchicago.edu
Received January 18, 2008. Revised May 7, 2008. Accepted May 8, 2008.
Fluorescence correlation spectroscopy (FCS) has permitted the characterization of high concentrations of noncoding RNAs in a single living bacterium. Here, we extend the use of FCS to low concentrations of coding RNAs in single living cells. We genetically fuse a red fluorescent protein (RFP) gene and two binding sites for an RNA-binding protein, whose translated product is the RFP protein alone. Using this construct, we determine in single cells both the absolute [mRNA] concentration and the associated [RFP] expressed from an inducible plasmid. We find that the FCS method allows us to reliably monitor in real-time [mRNA] down to
40 nM (i.e. approximately two transcripts per volume of detection). To validate these measurements, we show that [mRNA] is proportional to the associated expression of the RFP protein. This FCS-based technique establishes a framework for minimally invasive measurements of mRNA concentration in individual living bacteria.
Present addresses: Taejin L. Min, Department of Physics, 1110 West Green, University of Illinois at Urbana Champaign Urbana, IL 61801, USA
Thierry Emonet, MCDB, Yale University New Haven, CT 06510, USA