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  • 1
    Publication Date: 2002-05-25
    Description: A central problem in biology is determining how genes interact as parts of functional networks. Creation and analysis of synthetic networks, composed of well-characterized genetic elements, provide a framework for theoretical modeling. Here, with the use of a combinatorial method, a library of networks with varying connectivity was generated in Escherichia coli. These networks were composed of genes encoding the transcriptional regulators LacI, TetR, and lambda CI, as well as the corresponding promoters. They displayed phenotypic behaviors resembling binary logical circuits, with two chemical "inputs" and a fluorescent protein "output." Within this simple system, diverse computational functions arose through changes in network connectivity. Combinatorial synthesis provides an alternative approach for studying biological networks, as well as an efficient method for producing diverse phenotypes in vivo.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Guet, Calin C -- Elowitz, Michael B -- Hsing, Weihong -- Leibler, Stanislas -- New York, N.Y. -- Science. 2002 May 24;296(5572):1466-70.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Howard Hughes Medical Institute, Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/12029133" target="_blank"〉PubMed〈/a〉
    Keywords: Bacterial Proteins/genetics/metabolism ; Bacteriophage lambda/genetics ; Escherichia coli/*genetics/*metabolism ; *Escherichia coli Proteins ; Feedback, Physiological ; Fluorescence ; *Gene Expression Regulation, Bacterial ; Gene Library ; Genes, Regulator ; Green Fluorescent Proteins ; Lac Repressors ; Luminescent Proteins/genetics/metabolism ; Phenotype ; Plasmids ; *Promoter Regions, Genetic ; Repressor Proteins/*genetics/metabolism ; Signal Transduction ; Transformation, Bacterial
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 2
    Publication Date: 2010-11-16
    Description: The chemotaxis signalling network in Escherichia coli that controls the locomotion of bacteria is a classic model system for signal transduction. This pathway modulates the behaviour of flagellar motors to propel bacteria towards sources of chemical attractants. Although this system relaxes to a steady state in response to environmental changes, the signalling events within the chemotaxis network are noisy and cause large temporal variations of the motor behaviour even in the absence of stimulus. That the same signalling network governs both behavioural variability and cellular response raises the question of whether these two traits are independent. Here, we experimentally establish a fluctuation-response relationship in the chemotaxis system of living bacteria. Using this relationship, we demonstrate the possibility of inferring the cellular response from the behavioural variability measured before stimulus. In monitoring the pre- and post-stimulus switching behaviour of individual bacterial motors, we found that variability scales linearly with the response time for different functioning states of the cell. This study highlights that the fundamental relationship between fluctuation and response is not constrained to physical systems at thermodynamic equilibrium but is extensible to living cells. Such a relationship not only implies that behavioural variability and cellular response can be coupled traits, but it also provides a general framework within which we can examine how the selection of a network design shapes this interdependence.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3230254/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3230254/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Park, Heungwon -- Pontius, William -- Guet, Calin C -- Marko, John F -- Emonet, Thierry -- Cluzel, Philippe -- 1U54CA143869-01/CA/NCI NIH HHS/ -- P50 GM081892/GM/NIGMS NIH HHS/ -- P50 GM081892-04/GM/NIGMS NIH HHS/ -- R01 AI059195-03/AI/NIAID NIH HHS/ -- R01AI059195-03/AI/NIAID NIH HHS/ -- U54 CA143869/CA/NCI NIH HHS/ -- U54 CA143869-01/CA/NCI NIH HHS/ -- England -- Nature. 2010 Dec 9;468(7325):819-23. doi: 10.1038/nature09551. Epub 2010 Nov 14.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉The James Franck Institute, The Institute for Biophysical Dynamics, and The Department of Physics, University of Chicago, Chicago, Illinois 60637, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/21076396" target="_blank"〉PubMed〈/a〉
    Keywords: Aspartic Acid/metabolism/pharmacology ; Calibration ; Chemotaxis/drug effects/*physiology ; Chromatography, High Pressure Liquid ; *Environment ; Escherichia coli/*cytology/drug effects/*physiology ; Flagella/drug effects/physiology ; Molecular Motor Proteins/metabolism ; Rotation ; *Signal Transduction/drug effects ; Stochastic Processes ; Time Factors
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 3
    Publication Date: 2020
    Electronic ISSN: 2397-334X
    Topics: Biology
    Published by Springer Nature
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  • 4
    Publication Date: 2005-06-20
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
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  • 5
    Publication Date: 2016-02-20
    Description: Changes in gene expression are an important mode of evolution; however, the proximate mechanism of these changes is poorly understood. In particular, little is known about the effects of mutations within cis binding sites for transcription factors, or the nature of epistatic interactions between these mutations. Here, we tested the effects of single and double mutants in two cis binding sites involved in the transcriptional regulation of the Escherichia coli araBAD operon, a component of arabinose metabolism, using a synthetic system. This system decouples transcriptional control from any posttranslational effects on fitness, allowing a precise estimate of the effect of single and double mutations, and hence epistasis, on gene expression. We found that epistatic interactions between mutations in the araBAD cis- regulatory element are common, and that the predominant form of epistasis is negative. The magnitude of the interactions depended on whether the mutations are located in the same or in different operator sites. Importantly, these epistatic interactions were dependent on the presence of arabinose, a native inducer of the araBAD operon in vivo, with some interactions changing in sign (e.g., from negative to positive) in its presence. This study thus reveals that mutations in even relatively simple cis- regulatory elements interact in complex ways such that selection on the level of gene expression in one environment might perturb regulation in the other environment in an unpredictable and uncorrelated manner.
    Print ISSN: 0737-4038
    Electronic ISSN: 1537-1719
    Topics: Biology
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  • 6
    Publication Date: 2017-04-21
    Description: The molecular mechanisms underlying phenotypic variation in isogenic bacterial populations remain poorly understood. We report that AcrAB-TolC, the main multidrug efflux pump of Escherichia coli, exhibits a strong partitioning bias for old cell poles by a segregation mechanism that is mediated by ternary AcrAB-TolC complex formation. Mother cells inheriting old poles are phenotypically distinct and display increased drug efflux activity relative to daughters. Consequently, we find systematic and long-lived growth differences between mother and daughter cells in the presence of subinhibitory drug concentrations. A simple model for biased partitioning predicts a population structure of long-lived and highly heterogeneous phenotypes. This straightforward mechanism of generating sustained growth rate differences at subinhibitory antibiotic concentrations has implications for understanding the emergence of multidrug resistance in bacteria.
    Keywords: Cell Biology
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 7
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