UMass Chan Medical School Faculty Publications

UMMS Affiliation

Program in Systems Biology; Department of Microbiology and Physiological Systems

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Article Preprint


Systems Biology


The single-input module (SIM) is a regulatory motif capable of coordinating gene expression across functionally related genes. We explore the relationship between regulation of the central autoregulated TF in a negatively regulated SIM and the target genes using a synthetic biology approach paired with stochastic simulations. Surprisingly, we find a fundamental asymmetry in the level of regulation experienced by the TF gene and its targets, even if they have identical regulatory DNA; the TF gene experiences stronger repression than its targets. This asymmetry is not predicted from deterministic modeling of the system but is revealed from corresponding stochastic simulations. The magnitude of asymmetry depends on factors such as the number of targets in the SIM, TF degradation rate (or growth rate) and TF binding affinity. Beyond implications for SIM motifs, the influence of network connectivity on regulatory levels highlights an interesting challenge for predictive models of gene regulation.


regulatory asymmetry, single-input module, gene expression, synthetic biology, stochastic simulations, Systems Biology

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The copyright holder for this preprint (which was not peer-reviewed) is the author/funder. It is made available under a CC-BY-NC-ND 4.0 International license.

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bioRxiv 865527; doi: Link to preprint on bioRxiv service.

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Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.