Targeting Shiga Toxins for Treatment-resistant Bacterial Gut Infections
Technical Report,01 Jul 2018,30 Jun 2019
University of Utah Salt Lake City United States
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The purpose of this research is to identify a protease-resistant D-peptide inhibitor of Shiga toxin for use as an orally delivered prevention or therapeutic agent to treat severe bacterial gut infections caused by Shigella or Shiga toxin-producing E. coli STEC. During this period, we successfully synthesized the Shiga toxin B-subunit using solid-phase peptide synthesis and native chemical ligation. The N-terminal half of the protein suffers from poor solubility, so we developed a new helping hand solubilizing tag to enable isolation of this peptide and its ligation to the C-terminal half. This synthetic protein was folded into pentamers and validated using LCMS, circular dichroism, size-exclusion chromatography, and analytical ultracentrifugation. To overcome problems with instability of the pentamer, we developed a cork peptide that mimics the C-terminal tail of the natural Shiga A subunit. This peptide will stabilize the B-subunit pentamer by filling its central cavity. This stabilized pentamer will be used in mirror-image phage display to identify D-peptide inhibitors.