The genome of coronaviruses, including SARS‐CoV‐2, encodes for two proteases, a papain like (PL^pro) protease and the so‐called main protease (M^pro), a chymotrypsin‐like cysteine protease, also named 3CL^pro or non‐structural protein 5 (nsp5). M^pro is activated by autoproteolysis and is the main protease responsible for cutting the viral polyprotein into functional units. Aside from this, it is described that M^pro proteases are also capable of processing host proteins, including those involved in the host innate immune response. To identify substrates of the three main proteases from SARS‐CoV, SARS‐CoV‐2, and hCoV‐NL63 coronviruses, an LC‐MS based N‐terminomics in vitro analysis is performed using recombinantly expressed proteases and lung epithelial and endothelial cell lysates as substrate pools. For SARS‐CoV‐2 M^pro, 445 cleavage events from more than 300 proteins are identified, while 151 and 331 M^pro derived cleavage events are identified for SARS‐CoV and hCoV‐NL63, respectively. These data enable to better understand the cleavage site specificity of the viral proteases and will help to identify novel substrates in vivo. All data are available via ProteomeXchange with identifier PXD021406.

中文翻译：

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N-Terminomics 用于鉴定 SARS-CoV-2 主要蛋白酶的体外底物和切割位点特异性

冠状病毒的基因组，包括 SARS-CoV-2，编码两种蛋白酶，一种木瓜蛋白酶 (PL ^pro ) 蛋白酶和所谓的主蛋白酶 (M ^pro )，一种糜蛋白酶样半胱氨酸蛋白酶，也称为 3CL ^pro或非-结构蛋白 5 (nsp5)。M ^pro被自身蛋白水解激活，是负责将病毒多蛋白切割成功能单元的主要蛋白酶。除此之外，据说M ^pro蛋白酶还能够加工宿主蛋白质，包括那些参与宿主先天免疫反应的蛋白质。为了鉴定来自 SARS-CoV、SARS-CoV-2 和 hCoV-NL63 冠状病毒的三种主要蛋白酶的底物，使用重组表达的蛋白酶和肺上皮和内皮细胞裂解物进行了基于 LC-MS 的 N 末端组学体外分析底物池。对于 SARS-CoV-2 M ^pro，鉴定出来自 300 多种蛋白质的 445 个切割事件，而SARS-CoV 和 hCoV-NL63 分别鉴定出151 个和 331 M ^{pro衍生的切割事件。}这些数据能够更好地了解病毒蛋白酶的切割位点特异性，并将有助于在体内鉴定新的底物。所有数据均可通过 ProteomeXchange 获得，标识符为 PXD021406。