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Functional Characterization of Endogenously Expressed Human RYR1 Variants
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AraC regulatory protein mutants with altered effector specificity.

Shuang-Yan Tang1, Hossein Fazelinia, Patrick C Cirino

  • 1Department of Chemical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA.

Journal of the American Chemical Society
|March 22, 2008
PubMed
Summary

Researchers engineered the AraC regulatory protein to respond to D-arabinose instead of L-arabinose, creating novel gene switches. This breakthrough enables precise control for metabolic engineering applications.

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Area of Science:

  • Molecular Biology
  • Synthetic Biology
  • Microbial Engineering

Background:

  • The AraC protein regulates the Escherichia coli ara operon, typically responding to L-arabinose.
  • Engineering transcription factors for altered effector specificity is crucial for synthetic biology.

Purpose of the Study:

  • To engineer the AraC protein to activate transcription in response to D-arabinose, switching its effector specificity from L-arabinose.
  • To develop novel molecular tools for in vivo gene regulation and metabolic engineering.

Main Methods:

  • Construction and screening of two AraC mutant libraries with randomized binding pocket residues.
  • Utilizing Fluorescence-Activated Cell Sorting (FACS) with a GFP reporter for dual screening.
  • Testing mutant responses to various sugars and optimizing D-arabinose induction with the FucP transporter.

Main Results:

  • Identified AraC mutants exhibiting D-arabinose-specific transcriptional activation, with retained tight repression in the absence of effector.
  • Confirmed that L-arabinose and other tested sugars do not induce the engineered mutants.
  • Achieved D-arabinose induction in the millimolar range (0.1 mM) upon co-expression of the FucP transporter.

Conclusions:

  • Dual screening is a powerful method for altering the inducer specificity of regulatory proteins like AraC.
  • The engineered AraC variants represent significant progress toward creating customized in vivo molecular reporters and gene switches.
  • These engineered proteins have potential applications in metabolic engineering and precise biological control systems.