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Publication Abstract from PubMed

A critical step for SARS-CoV-2 assembly and maturation involves the autoactivation of the main protease (MPro(WT)) from precursor polyproteins. Upon expression, a model precursor of MPro(WT) mediates its own release at its termini rapidly to yield a mature dimer. A construct with an E290A mutation within MPro exhibits time dependent autoprocessing of the accumulated precursor at the N-terminal nsp4/nsp5 site followed by the C-terminal nsp5/nsp6 cleavage. In contrast, a precursor containing E290A and R298A mutations (MPro(M)) displays cleavage only at the nsp4/nsp5 site to yield an intermediate monomeric product, which is cleaved at the nsp5/nsp6 site only by MPro(WT). MPro(M) and the catalytic domain (MPro(1-199)) fused to the truncated nsp4 region also show time-dependent conversion in vitro to produce MPro(M) and MPro(1-199), respectively. The reactions follow first-order kinetics indicating that the nsp4/nsp5 cleavage occurs via an intramolecular mechanism. These results support a mechanism involving an N-terminal intramolecular cleavage leading to an increase in the dimer population and followed by an intermolecular cleavage at the C-terminus. Thus, targeting the predominantly monomeric MPro precursor for inhibition may lead to the identification of potent drugs for treatment.

Insights into the mechanism of SARS-CoV-2 main protease autocatalytic maturation from model precursors.,Aniana A, Nashed NT, Ghirlando R, Coates L, Kneller DW, Kovalevsky A, Louis JM Commun Biol. 2023 Nov 13;6(1):1159. doi: 10.1038/s42003-023-05469-8. PMID:37957287^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.