Structure-Based Design of Potent Peptidomimetic Inhibitors Covalently Targeting SARS-CoV-2 Papain-like Protease.

The papain-like protease (PLpro) of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) plays a critical role in the proteolytic processing of viral polyproteins and the dysregulation of the host immune response, providing a promising therapeutic target. Here, we report the structure-guide design of novel peptidomimetic inhibitors covalently targeting SARS-CoV-2 PLpro. The resulting inhibitors demonstrate submicromolar potency in the enzymatic assay (IC50 = 0.23 µM) and significant inhibition of SARS-CoV-2 PLpro in the HEK293T cells using a cell-based protease assay (EC50 = 3.61 µM). Moreover, an X-ray crystal structure of SARS-CoV-2 PLpro in complex with compound 2 confirms the covalent binding of the inhibitor to the catalytic residue cysteine 111 (C111) and emphasizes the importance of interactions with tyrosine 268 (Y268). Together, our findings reveal a new scaffold of SARS-CoV-2 PLpro inhibitors and provide an attractive starting point for further optimization.

Identification of Cysteine 270 as a Novel Site for Allosteric Modulators of SARS‐CoV‐2 Papain‐Like Protease**

The coronavirus papain‐like protease (PLpro) plays an important role in the proteolytic processing of viral polyproteins and the dysregulation of the host immune response, providing a promising therapeutic target. However, the development of inhibitors against severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) PLpro is challenging owing to the restricted S1/S2 sites in the substrate binding pocket. Here we report the discovery of two activators of SARS‐CoV‐2 PLpro and the identification of the unique residue, cysteine 270 (C270), as an allosteric and covalent regulatory site for the activators. This site is also specifically modified by glutathione, resulting in protease activation. Furthermore, a compound was found to allosterically inhibit the protease activity by covalent binding to C270. Together, these results elucidate an unrevealed molecular mechanism for allosteric modulation of SARS‐CoV‐2 PLpro and provid a novel site for allosteric inhibitors design. [ FROM AUTHOR]

Identification of Cysteine 270 as a Novel Site for Allosteric Modulators of SARS-CoV-2 Papain-Like Protease.

The coronavirus papain-like protease (PLpro ) plays an important role in the proteolytic processing of viral polyproteins and the dysregulation of the host immune response, providing a promising therapeutic target. However, the development of inhibitors against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) PLpro is challenging owing to the restricted S1/S2 sites in the substrate binding pocket. Here we report the discovery of two activators of SARS-CoV-2 PLpro and the identification of the unique residue, cysteine 270 (C270), as an allosteric and covalent regulatory site for the activators. This site is also specifically modified by glutathione, resulting in protease activation. Furthermore, a compound was found to allosterically inhibit the protease activity by covalent binding to C270. Together, these results elucidate an unrevealed molecular mechanism for allosteric modulation of SARS-CoV-2 PLpro and provid a novel site for allosteric inhibitors design.

Prediction for Progression Risk in Patients With COVID-19 Pneumonia: The CALL Score.

BACKGROUND: We aimed to clarify high-risk factors for coronavirus disease 2019 (COVID-19) with multivariate analysis and establish a predictive model of disease progression to help clinicians better choose a therapeutic strategy. METHODS: All consecutive patients with COVID-19 admitted to Fuyang Second People's Hospital or the Fifth Medical Center of Chinese PLA General Hospital between 20 January and 22 February 2020 were enrolled and their clinical data were retrospectively collected. Multivariate Cox regression was used to identify risk factors associated with progression, which were then were incorporated into a nomogram to establish a novel prediction scoring model. ROC was used to assess the performance of the model. RESULTS: Overall, 208 patients were divided into a stable group (n = 168, 80.8%) and a progressive group (n = 40,19.2%) based on whether their conditions worsened during hospitalization. Univariate and multivariate analyses showed that comorbidity, older age, lower lymphocyte count, and higher lactate dehydrogenase at presentation were independent high-risk factors for COVID-19 progression. Incorporating these 4 factors, the nomogram achieved good concordance indexes of .86 (95% confidence interval [CI], .81-.91) and well-fitted calibration curves. A novel scoring model, named as CALL, was established; its area under the ROC was .91 (95% CI, .86-.94). Using a cutoff of 6 points, the positive and negative predictive values were 50.7% (38.9-62.4%) and 98.5% (94.7-99.8%), respectively. CONCLUSIONS: Using the CALL score model, clinicians can improve the therapeutic effect and reduce the mortality of COVID-19 with more accurate and efficient use of medical resources.