Biological Functions Of Papain-Like Protease Of Human Coronavirus NL63

This project researches on papain-like protease of human coronavirus NL63. We constructed the mutants PLP1 D1225A and PLP2 D1849A. Western Blotting assay showed that PLP2 and PLP2 D1849A not PLP1 and its mutants have deubiquitinating(DUB) activity. Meanwhile, ubiquitin-like molecule the interferon sitimulate gene (ISG) was detected, we proved that PLP2 has deISGylation activity. It was suggested that the DUB activity of PLP2 is not dependent on its protease activity perfectly C1678A and H1836A are necessary for its DUB activity, but not D1849A.The research on PLP regulating innate immune response revealed that PLP2 not PLP1 supresses interferon (IFN) production, and this activity doesn't dependent on PLP2 C1678 and PLP2 H1836. The results indicated that the IFN antagonist activity of PLP2 is related with its DUB activity. Further research manifested that PLP2 supresses IFN expression pathway by deubiquitinating of the retinoic acid inducible gene I (RIG-I) and the endoplasmic reticulum IFN stimulator (ERIS).