Outer-Membrane Protease (OmpT) Based E. coli Sensing with Anionic Polythiophene and Unlabeled Peptide Substrate

Gaurav Sinsinbar, Sushanth Gudlur, Sarah E. Wood, Gopal Ammanath, Hakan U. Yildiz, Palaniappan Alagappan, Milan Mrksich, Bo Liedberg*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


E. coli and Salmonella are two of the most common bacterial pathogens involved in foodborne and waterborne related deaths. Hence, it is critical to develop rapid and sensitive detection strategies for near-outbreak applications. Reported is a simple and specific assay to detect as low as 1 CFU mL−1 of E. coli in water within 6 hours by targeting the bacteria's surface protease activity. The assay relies on polythiophene acetic acid (PTAA) as an optical reporter and a short unlabeled peptide (LL37FRRV) previously optimized as a substrate for OmpT, an outer-membrane protease on E. coli. LL37FRRV interacts with PTAA to enhance its fluorescence while also inducing the formation of a helical PTAA-LL37FRRV construct, as confirmed by circular dichroism. However, in the presence of E. coli LL37FRRV is cleaved and can no longer affect the conformations and optical properties of PTAA. This ability to distinguish between an intact and cleaved peptide was investigated in detail using LL37FRRV sequence variants.

Original languageEnglish (US)
Pages (from-to)18068-18077
Number of pages10
JournalAngewandte Chemie - International Edition
Issue number41
StatePublished - Oct 5 2020


  • enzymes
  • fluorescence
  • membrane proteins
  • pathogens
  • peptides

ASJC Scopus subject areas

  • Chemistry(all)
  • Catalysis


Dive into the research topics of 'Outer-Membrane Protease (OmpT) Based E. coli Sensing with Anionic Polythiophene and Unlabeled Peptide Substrate'. Together they form a unique fingerprint.

Cite this