title: Gene regulation and noise reduction by coupling of stochastic processes.
abstract: Here we characterize the low-noise regime of a stochastic model for a negative self-regulating binary gene. The model has two stochastic variables, the protein number and the state of the gene. Each state of the gene behaves as a protein source governed by a Poisson process. The coupling between the two gene states depends on protein number. This fact has a very important implication: There exist protein production regimes characterized by sub-Poissonian noise because of negative covariance between the two stochastic variables of the model. Hence the protein numbers obey a probability distribution that has a peak that is sharper than those of the two coupled Poisson processes that are combined to produce it. Biochemically, the noise reduction in protein number occurs when the switching of the genetic state is more rapid than protein synthesis or degradation. We consider the chemical reaction rates necessary for Poisson and sub-Poisson processes in prokaryotes and eucaryotes. Our results suggest that the coupling of multiple stochastic processes in a negative covariance regime might be a widespread mechanism for noise reduction.
authors.affiliation: Departamento de Radiologia, Faculdade de Medicina, Núcleo de Estudos Interdisciplinares em Sistemas Complexos, Escola de Artes, Ciências e Humanidades, Universidade de São Paulo, Avenida Arlindo Béttio 1000, CEP 03828-000, São Paulo, São Paulo, Brazil.
authors.forename: Alexandre F
authors.initials: AF
authors.lastname: Ramos
authors.affiliation: Instituto de Física de São Carlos, Universidade de São Paulo, Caixa Postal 369, 13560-970 São Carlos, São Paulo, Brazil.
authors.forename: José Eduardo M
authors.initials: JE
authors.lastname: Hornos
authors.affiliation: Department of Statistics, Department of Ecology and Evolution, Department of Molecular Genetics and Cell Biology, and the Institute of Genomics and Systems Biology, University of Chicago, 5734 South University Avenue, Chicago, Illinois 60637, USA.
authors.forename: John
authors.initials: J
authors.lastname: Reinitz
mesh_terms: D005057:Eukaryotic Cells / Q000378:metabolism; D005786:Gene Expression Regulation / Q000502:physiology; D008957:Models, Genetic; D016012:Poisson Distribution; D011336:Probability; D011387:Prokaryotic Cells / Q000378:metabolism; D011506:Proteins / Q000235:genetics / Q000378:metabolism; D013269:Stochastic Processes
chemical_list: D011506:Proteins