Isomorphic Fluorescent Nucleosides Facilitate Real-Time Monitoring of RNA Depurination by Ribosome Inactivating Proteins |
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Authors: | Deyuan Cong Dr Yao Li Paul T Ludford III Prof Dr Yitzhak Tor |
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Institution: | Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093-0358 USA |
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Abstract: | Ribosome-inactivating proteins, a family of highly cytotoxic proteins, interfere with protein synthesis by depurinating a specific adenosine residue within the conserved α-sarcin/ricin loop of eukaryotic ribosomal RNA. Besides being biological warfare agents, certain RIPs have been promoted as potential therapeutic tools. Monitoring their deglycosylation activity and their inhibition in real time have remained, however, elusive. Herein, we describe the enzymatic preparation and utility of consensus RIP hairpin substrates in which specific G residues, next to the depurination site, are surgically replaced with tzG and thG, fluorescent G analogs. By strategically modifying key positions with responsive fluorescent surrogate nucleotides, RIP-mediated depurination can be monitored in real time by steady-state fluorescence spectroscopy. Subtle differences observed in preferential depurination sites provide insight into the RNA folding as well as RIPs’ substrate recognition features. |
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Keywords: | emissive nucleosides fluorescence kinetics protein toxins RNA |
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