Remote control of cells is a desirable feature in synthetic biology. We established a light-switchable interfering peptide (iPEP) which controls gene expression by modulating the activity of a transcription factor. For photo-switching, the iPEP is cross-linked with a cis-trans isomerizable cross-linker in such a way that the light-activated cis form enables inhibitor folding rendering it active, whereas the dark-adapted trans form forces the inhibitor into an inactive form. Switching can be repeated in both directions. The iPEP acts as dominant-negative inhibitor targeting c-Jun and c-Fos of the transcription factor activator protein-1 (AP-1). Light-activated peptides exhibited much stronger inhibition of AP-1:DNA complexes and interference with gene transcription than their nonactivated counter parts. In this chapter, we provide protocols for cross-linking, peptide purification, observation of structural changes upon photo-switching, DNA binding analyses as well as gene expression studies in mammalian cells.

Original languageEnglish
Title of host publicationSynthetic Gene Networks
Subtitle of host publicationMethods and Protocols
EditorsWilfried Weber, Martin Fussenegger, Wilfried Weber
Number of pages16
StatePublished - 2012

Publication series

NameMethods in Molecular Biology
ISSN (Print)1064-3745


  • cis-trans Isomerization
  • Electrophoretic mobility shift assay
  • Inducible gene expression
  • Interfering peptide
  • Light-switchable


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