Systems and Synthetic Biology

, Volume 1, Issue 2, pp 89–98

Designing sequential transcription logic: a simple genetic circuit for conditional memory

  • Georg Fritz
  • Nicolas E. Buchler
  • Terence Hwa
  • Ulrich Gerland
Research article

DOI: 10.1007/s11693-007-9006-8

Cite this article as:
Fritz, G., Buchler, N.E., Hwa, T. et al. Syst Synth Biol (2007) 1: 89. doi:10.1007/s11693-007-9006-8

Abstract

The ability to learn and respond to recurrent events depends on the capacity to remember transient biological signals received in the past. Moreover, it may be desirable to remember or ignore these transient signals conditioned upon other signals that are active at specific points in time or in unique environments. Here, we propose a simple genetic circuit in bacteria that is capable of conditionally memorizing a signal in the form of a transcription factor concentration. The circuit behaves similarly to a “data latch” in an electronic circuit, i.e. it reads and stores an input signal only when conditioned to do so by a “read command.” Our circuit is of the same size as the well-known genetic toggle switch (an unconditional latch) which consists of two mutually repressing genes, but is complemented with a “regulatory front end” involving protein heterodimerization as a simple way to implement conditional control. Deterministic and stochastic analysis of the circuit dynamics indicate that an experimental implementation is feasible based on well-characterized genes and proteins. It is not known, to which extent molecular networks are able to conditionally store information in natural contexts for bacteria. However, our results suggest that such sequential logic elements may be readily implemented by cells through the combination of existing protein–protein interactions and simple transcriptional regulation.

Keywords

Gene regulation Sequential logic Quantitative modeling Synthetic biology 

Supplementary material

11693_2007_9006_MOESM1_ESM.pdf (1.7 mb)
Supplementary material

Copyright information

© Springer Science + Business Media B.V. 2007

Authors and Affiliations

  • Georg Fritz
    • 1
    • 2
  • Nicolas E. Buchler
    • 3
  • Terence Hwa
    • 4
  • Ulrich Gerland
    • 1
  1. 1.Institute for Theoretical PhysicsUniversität zu KölnKölnGermany
  2. 2.Department of Physics and CeNSLMU MünchenMunichGermany
  3. 3.Center for Studies in Physics and BiologyThe Rockefeller UniversityNew YorkUSA
  4. 4.Center for Theoretical Biological Physics and Physics DepartmentUniversity of California at San DiegoLa Jolla, San DiegoUSA

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