A Stochastic Single-Molecule Event Triggers Phenotype Switching of a Bacterial Cell

By monitoring fluorescently labeled lactose permease with single-molecule sensitivity, we investigated the molecular mechanism of how an Escherichia coli cell with the lac operon switches from one phenotype to another. At intermediate inducer concentrations, a population of genetically identical cells exhibits two phenotypes: induced cells with highly fluorescent membranes and uninduced cells with a small number of membrane-bound permeases. We found that this basal-level expression results from partial dissociation of the tetrameric lactose repressor from one of its operators on looped DNA. In contrast, infrequent events of complete dissociation of the repressor from DNA result in large bursts of permease expression that trigger induction of the lac operon. Hence, a stochastic single-molecule event determines a cell's phenotype.

[1]  F. Young.  Biochemistry , 1955, The Indian Medical Gazette.

[2]  A. Novick,et al.  ENZYME INDUCTION AS AN ALL-OR-NONE PHENOMENON. , 1957, Proceedings of the National Academy of Sciences of the United States of America.

[3]  J. Monod,et al.  Genetic regulatory mechanisms in the synthesis of proteins. , 1961, Journal of molecular biology.

[4]  W. Gilbert,et al.  ISOLATION OF THE LAC REPRESSOR , 1966, Proceedings of the National Academy of Sciences of the United States of America.

[5]  A. Riggs,et al.  Interaction of effecting ligands with lac repressor and repressor-operator complex. , 1975, Biochemistry.

[6]  P. V. von Hippel,et al.  Direct measurement of association constants for the binding of Escherichia coli lac repressor to non-operator DNA. , 1977, Biochemistry.

[7]  B. Bainbridge,et al.  Genetics , 1981, Experientia.

[8]  H. Riezman,et al.  Transcription and translation initiation frequencies of the Escherichia coli lac operon. , 1977, Journal of molecular biology.

[9]  J M Rosenberg,et al.  Kinetic studies of inducer binding to lac repressor.operator complex. , 1980, The Journal of biological chemistry.

[10]  B. Müller-Hill,et al.  lac repressor forms loops with linear DNA carrying two suitably spaced lac operators. , 1987, The EMBO journal.

[11]  B. Müller-Hill,et al.  The three operators of the lac operon cooperate in repression. , 1990, The EMBO journal.

[12]  B. Müller-Hill.  The lac Operon: A Short History of a Genetic Paradigm , 1996 .

[13]  Stanislas Leibler,et al.  Modeling network dynamics , 2003, The Journal of cell biology.

[14]  Mark Ptashne,et al.  A Genetic Switch, Phage Lambda Revisited , 2004 .

[15]  Ertugrul M. Ozbudak,et al.  Multistability in the lactose utilization network of Escherichia coli , 2004, Nature.

[16]  P. Swain,et al.  Gene Regulation at the Single-Cell Level , 2005, Science.

[17]  宁北芳,et al.  疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A , 2005 .

[18]  T. Elston,et al.  Stochasticity in gene expression: from theories to phenotypes , 2005, Nature Reviews Genetics.

[19]  J. Onuchic,et al.  Self-regulating gene: an exact solution. , 2005, Physical review. E, Statistical, nonlinear, and soft matter physics.

[20]  U. Alon,et al.  Optimality and evolutionary tuning of the expression level of a protein , 2005, Nature.

[21]  X. Xie,et al.  Probing Gene Expression in Live Cells, One Protein Molecule at a Time , 2006, Science.

[22]  R. Losick,et al.  Bistability in bacteria , 2006, Molecular microbiology.

[23]  N. Friedman,et al.  Stochastic protein expression in individual cells at the single molecule level , 2006, Nature.

[24]  Ertugrul M. Ozbudak,et al.  Predicting stochastic gene expression dynamics in single cells. , 2006, Proceedings of the National Academy of Sciences of the United States of America.

[25]  Nir Friedman,et al.  Linking stochastic dynamics to population distribution: an analytical framework of gene expression. , 2006, Physical review letters.

[26]  Jayajit Das,et al.  Purely stochastic binary decisions in cell signaling models without underlying deterministic bistabilities , 2007, Proceedings of the National Academy of Sciences.

[27]  J. Elf,et al.  Probing Transcription Factor Dynamics at the Single-Molecule Level in a Living Cell , 2007, Science.

[28]  Nam Ki Lee,et al.  Single-molecule approach to molecular biology in living bacterial cells. , 2008, Annual review of biophysics.

[29]  R. Rosenfeld.  Nature , 2009, Otolaryngology--head and neck surgery : official journal of American Academy of Otolaryngology-Head and Neck Surgery.