second ubiquitin-like (Ubl) domain located N-terminal to the papain-like protease (PLpro) domain in coronavirus non-structural protein 3 (Nsp3) and related proteins
This model represents the second ubiquitin-like (Ubl) domain located N-terminal to the papain-like protease (PLpro) domain of non-structural protein 3 (Nsp3) from coronavirus (CoV), including highly pathogenic human CoVs such as Severe acute respiratory syndrome (SARS)-CoV and SARS-CoV-2 (also known as 2019 novel CoV (2019-nCoV) or COVID-19 virus). SARS-CoV non-structural proteins (Nsps) are encoded in ORF1a and ORF1b. Post infection, the SARS-CoV genomic RNA is released into the cytoplasm of the cell and translated into two long polyproteins (pps), pp1a and pp1ab. Papain-like protease (PLpro) is one of two SARS-CoV proteases which process these polyproteins; it cleaves pp1a at three sites, releasing Nsp1, Nsp2, and Nsp3. Nsp3 is a large multi-functional multi-domain protein which is an essential component of the replication/transcription complex (RTC). This ubiquitin-like (Ubl) domain (sometimes referred to as Ubl2, the second Ubl domain of Nsp3) is located N-terminal to the PLpro domain of Nsp3. In addition to being a protease, SARS-CoV PLpro is a deubiquitinating enzyme (DUB), and may be involved in subverting cellular ubiquitination machinery to facilitate viral replication. A number of cellular DUBs have a Ubl domain, where it may serve a regulatory function. The exact functional role of this Ubl domain is unclear.
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