title: Gene regulation at the single-cell level.
abstract: The quantitative relation between transcription factor concentrations and the rate of protein production from downstream genes is central to the function of genetic networks. Here we show that this relation, which we call the gene regulation function (GRF), fluctuates dynamically in individual living cells, thereby limiting the accuracy with which transcriptional genetic circuits can transfer signals. Using fluorescent reporter genes and fusion proteins, we characterized the bacteriophage lambda promoter P(R) in Escherichia coli. A novel technique based on binomial errors in protein partitioning enabled calibration of in vivo biochemical parameters in molecular units. We found that protein production rates fluctuate over a time scale of about one cell cycle, while intrinsic noise decays rapidly. Thus, biochemical parameters, noise, and slowly varying cellular states together determine the effective single-cell GRF. These results can form a basis for quantitative modeling of natural gene circuits and for design of synthetic ones.
authors.affiliation: Departments of Molecular Cell Biology and Physics of Complex Systems, Weizmann Institute of Science, Rehovot, 76100, Israel.
authors.forename: Nitzan
authors.initials: N
authors.lastname: Rosenfeld
authors.forename: Jonathan W
authors.initials: JW
authors.lastname: Young
authors.forename: Uri
authors.initials: U
authors.lastname: Alon
authors.forename: Peter S
authors.initials: PS
authors.lastname: Swain
authors.forename: Michael B
authors.initials: MB
authors.lastname: Elowitz
mesh_terms: D001426:Bacterial Proteins / Q000096:biosynthesis; D010582:Bacteriophage lambda / Q000235:genetics; D002453:Cell Cycle; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000096:biosynthesis / Q000378:metabolism*; D005453:Fluorescence; D015964:Gene Expression Regulation, Bacterial; D049452:Green Fluorescent Proteins / Q000096:biosynthesis; D007091:Image Processing, Computer-Assisted; D008164:Luminescent Proteins / Q000096:biosynthesis; D008433:Mathematics; D008856:Microscopy, Fluorescence; D008957:Models, Genetic; D011401:Promoter Regions, Genetic; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012097:Repressor Proteins / Q000378:metabolism*; D015398:Signal Transduction; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic; D014764:Viral Proteins; D054334:Viral Regulatory and Accessory Proteins
chemical_list: D001426:Bacterial Proteins; C485182:Cyan Fluorescent Protein; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D008164:Luminescent Proteins; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; D014764:Viral Proteins; D054334:Viral Regulatory and Accessory Proteins; C016649:phage repressor proteins; C054562:yellow fluorescent protein, Bacteria; D049452:Green Fluorescent Proteins