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Distinct noise-controlling roles of multiple negative feedback mechanisms in a prokaryotic operon system
Author(s)
Date Issued
2011-03-01
Date Available
2013-11-28T17:35:08Z
Abstract
Molecular fluctuations are known to affect dynamics of cellular systems in important ways. Studies aimed at understanding how molecular systems of certain regulatory architectures control noise therefore become essential. The interplay between feedback regulation and noise has been previously explored for cellular networks governed by a single negative feedback loop. However, similar issues within networks consisting of more complex regulatory structures remain elusive. The authors investigate how negative feedback loops manage noise within a biochemical cascade concurrently governed by multiple negative feedback loops, using the prokaryotic tryptophan (trp) operon system in Escherechia coli as the model system. To the authors knowledge, this is the first study of noise in the trp operon system. They show that the loops in the trp operon system possess distinct, even opposing, noise-controlling effects despite their seemingly analogous feedback structures. The enzyme inhibition loop, although controlling the last reaction of the cascade, was found to suppress noise not only for the tryptophan output but also for other upstream components. In contrast, the Repression (Rep) loop enhances noise for all systems components. Attenuation (Att) poses intermediate effects by attenuating noise for the upstream components but promoting noise for components downstream of its target. Regarding noise at the output tryptophan, Rep and Att can be categorised as noise-enhancing loops whereas Enzyme Inhibition as a noise-reducing loop. These findings suggest novel implications in how cellular systems with multiple feedback mechanisms control noise.
Type of Material
Journal Article
Publisher
Institution of Electrical Engineers
Journal
IET Systems Biology
Volume
5
Issue
2
Start Page
145
End Page
156
Copyright (Published Version)
2011 Institution of Electrical Engineers
Language
English
Status of Item
Peer reviewed
This item is made available under a Creative Commons License
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