RNA-controlled synthesis of peptides via peptidyl transfer reactions with peptide-nucleic acid conugates

• Applicant: Professor Dr. Oliver Seitz
• Subject Area: Biological and Biomimetic Chemistry ; Organic Molecular Chemistry - Synthesis and Characterisation
• Term: from 2012 to 2016
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 225213878

It is the aim to develop a reaction, which proceeds only when a specific RNA sequence is present and leads to the formation of a biologically active compound. This is accomplished by means of a RNA-triggered peptidyl transfer reaction, which bears resemblance to a key step in ribosomal peptide synthesis. The reaction involves a donor peptide, which is connected via a thioester bond to a peptide nucleic acid (PNA) unit. A second peptide-PNA conjugate offers a reactive 1,2- or 1,3-aminothiol structure at the N-terminal end and serves as acceptor. The two conjugates bind adjacently to a complementary RNA template. This triggers the intramolecular transfer of the donor onto the acceptor peptide. A new peptide bond is formed in a native chemical ligation like reaction. The prerequisites for efficient peptidyl transfer are examined by varying the architecture of the RNA templates, the length of the donor and acceptor peptides as well as the structure of the thioesters involved. The RNA-triggered peptidyl transfer may provide new opportunities for the development of a) artificial feedback loops in synthetic biology and b) cell type specific, personalized bioactive compounds. It is the long-term objective to hijack cell endogenous RNA molecules and use the RNA sequence information for the programmed formation of compounds that modulate signal transduction e.g. in cancer cells. The RNA templates can act as catalysts which trigger the formation of many peptide molecules per template. The achievable turnover rate is an important reaction parameter given that the RNA target of interest may occur at low abundance. The in situ formed peptides will be used to inhibit Bcl-xL; a protein that prevents apoptosis in cancer cells. Further efforts are directed to the RNA-induced synthesis of a phosphopeptide that inhibits the Signal Transduction and Activator of Transcription 3 (Stat3). The ability to translate RNA information into protein inhibition will be assessed in protein binding assays which involve recombinant proteins and proteins in cell lysates.

• DFG Programme: Research Grants