Probing gene expression in live cells, one protein molecule at a time.
We directly observed real-time production of single protein molecules in individual Escherichia coli cells. A fusion protein of a fast-maturing yellow fluorescent protein (YFP) and a membrane-targeting peptide was expressed under a repressed condition. The membrane-localized YFP can be detected with single-molecule sensitivity. We found that the protein molecules are produced in bursts, with each burst originating from a stochastically transcribed single messenger RNA molecule, and that protein copy numbers in the bursts follow a geometric distribution. The quantitative study of low-level gene expression demonstrates the potential of single-molecule experiments in elucidating the workings of fundamental biological processes in living cells.
Yu
Ji
J
Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA.
Xiao
Jie
J
Ren
Xiaojia
X
Lao
Kaiqin
K
Xie
X Sunney
XS
D001426:Bacterial Proteins / Q000032:analysis / Q000096:biosynthesis / Q000235:genetics; D015153:Blotting, Western; D048168:Escherichia coli K12 / Q000235:genetics* / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000032:analysis / Q000096:biosynthesis* / Q000235:genetics; D005453:Fluorescence; D015870:Gene Expression; D020869:Gene Expression Profiling / Q000379:methods*; D008164:Luminescent Proteins / Q000032:analysis / Q000096:biosynthesis / Q000235:genetics; D008565:Membrane Proteins / Q000032:analysis / Q000096:biosynthesis / Q000235:genetics; D008856:Microscopy, Fluorescence; D015336:Molecular Probe Techniques; D016012:Poisson Distribution; D011401:Promoter Regions, Genetic; D012329:RNA, Bacterial / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000032:analysis / Q000096:biosynthesis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013269:Stochastic Processes
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D008164:Luminescent Proteins; D008565:Membrane Proteins; D012329:RNA, Bacterial; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; C057635:Tsr protein, Bacteria; C054562:yellow fluorescent protein, Bacteria