Biochemical Strategy to Avert Microbial Drug Resistance

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PROJECT SUMMARY/ABSTRACT The goal of the proposed research is to develop a generalizable antimicrobial strategy that averts the onset of resistance. The proposed antiviral agent has a mechanism of action that relies on the function of a pathogenic protein rather than its inhibition. Specifically, the agent is a cytotoxic variant of a human enzyme, ribonuclease 1 (RNase 1), that is cloaked and thus inactive as a catalyst. The cloak is removable only by a pathogenic protease that is essential for the lifecycle of the pathogen. SARS-CoV-2 will serve as a model pathogen in the study. The goal will be attained by (1) identifying an optimal amino acid sequence that is cleaved by the 3CLpro protease of SARS-CoV-2 but not by endogenous human proteases, (2) using that sequence and intein-mediated cis- splicing to create a cyclic RNase 1 zymogen, and (3) demonstrating the ability of the zymogen to kill human lung cells that express 3CLpro and that are infected by SARS-CoV-2. Because the activated zymogen can also destroy the genome of an RNA virus like SARS-CoV-2, it could eradicate the viral reservoir in patients. A notable feature of the strategy is its modularity: the protease-cleavage sequence is a cassette that can be altered to match the specificity of pathogenic proteases for the treatment of other infectious diseases.