6bi8
X-ray structure of MERS coronavirus papain-like protease in complex with human ISG15
Structural highlights
FunctionK0BWD0_MERS Cleaves the C-terminus of replicase polyprotein at 11 sites. Recognizes substrates containing the core sequence [ILMVF]-Q-|-[SGACN]. Also able to bind an ADP-ribose-1-phosphate (ADRP).[ARBA:ARBA00002223] Enzyme possessing two different activities: an exoribonuclease activity acting on both ssRNA and dsRNA in a 3' to 5' direction and a N7-guanine methyltransferase activity.[ARBA:ARBA00003995] Forms a hexadecamer with nsp7 (8 subunits of each) that may participate in viral replication by acting as a primase. Alternatively, may synthesize substantially longer products than oligonucleotide primers.[ARBA:ARBA00002182] Forms a hexadecamer with nsp8 (8 subunits of each) that may participate in viral replication by acting as a primase. Alternatively, may synthesize substantially longer products than oligonucleotide primers.[ARBA:ARBA00003443] May participate in viral replication by acting as a ssRNA-binding protein.[ARBA:ARBA00002012] May play a role in the modulation of host cell survival signaling pathway by interacting with host PHB and PHB2. Indeed, these two proteins play a role in maintaining the functional integrity of the mitochondria and protecting cells from various stresses.[ARBA:ARBA00003115] Methyltransferase that mediates mRNA cap 2'-O-ribose methylation to the 5'-cap structure of viral mRNAs. N7-methyl guanosine cap is a prerequisite for binding of nsp16. Therefore plays an essential role in viral mRNAs cap methylation which is essential to evade immune system.[ARBA:ARBA00002840] Multi-functional protein with a zinc-binding domain in N-terminus displaying RNA and DNA duplex-unwinding activities with 5' to 3' polarity. Activity of helicase is dependent on magnesium.[ARBA:ARBA00002960] Participates in the assembly of virally-induced cytoplasmic double-membrane vesicles necessary for viral replication.[ARBA:ARBA00003070] Plays a pivotal role in viral transcription by stimulating both nsp14 3'-5' exoribonuclease and nsp16 2'-O-methyltransferase activities. Therefore plays an essential role in viral mRNAs cap methylation.[ARBA:ARBA00002697] Plays a role in the initial induction of autophagosomes from host reticulum endoplasmic. Later, limits the expansion of these phagosomes that are no longer able to deliver viral components to lysosomes.[ARBA:ARBA00003748] Plays a role in viral transcription/replication and prevents the simultaneous activation of host cell dsRNA sensors, such as MDA5/IFIH1, OAS, and PKR (By similarity). Acts by degrading the 5'-polyuridines generated during replication of the poly(A) region of viral genomic and subgenomic RNAs. Catalyzes a two-step reaction in which a 2'3'-cyclic phosphate (2'3'-cP) is first generated by 2'-O transesterification, which is then hydrolyzed to a 3'-phosphate (3'-P) (By similarity). If not degraded, poly(U) RNA would hybridize with poly(A) RNA tails and activate host dsRNA sensors.[ARBA:ARBA00025521] Responsible for replication and transcription of the viral RNA genome.[ARBA:ARBA00003927] The replicase polyprotein of coronaviruses is a multifunctional protein: it contains the activities necessary for the transcription of negative stranded RNA, leader RNA, subgenomic mRNAs and progeny virion RNA as well as proteinases responsible for the cleavage of the polyprotein into functional products.[ARBA:ARBA00003368] Publication Abstract from PubMedCoronavirus papain-like proteases (PLPs or PLpro), such as the one encoded in the genome of the infectious Middle East Respiratory Syndrome (MERS) virus, have multiple enzymatic activities that promote viral infection. PLpro acts as a protease and processes the large coronavirus polyprotein for virus replication. PLpro also functions as both a deubiquitinating (DUB) and deISGylating (deISG) enzyme and removes ubiquitin (Ub) and interferon-stimulated gene 15 (ISG15) from cellular proteins. Both DUB and deISG activities are implicated in suppressing innate immune responses; however, the precise role of each activity in this process is still unclear due in part to the difficulties in separating each activity. In this study, we determine the first structure of MERS PLpro in complex with the full-length human ISG15 to a resolution of 2.3 A. This structure and available structures of MERS PLpro-Ub complexes were used as molecular guides to design PLpro mutants that lack either or both DUB/deISG activities. We tested 13 different PLpro mutants for protease, DUB, and deISG activitites using fluorescence-based assays. Results show that we can selectively modulate DUB activity at amino acid positions 1649 and 1653 while mutation of Val1691 or His1652 of PLpro to a positive charged residue completely impairs both DUB/deISG activities. These mutant enzymes will provide new functional tools for delineating the importance of DUB versus deISG activity in virus-infected cells and may serve as potential candidates for attenuating the MERS virus in vivo for modified vaccine design efforts. Decoupling deISGylating and deubiquitinating activities of the MERS virus papain-like protease.,Clasman JR, Everett RK, Srinivasan K, Mesecar AD Antiviral Res. 2020 Feb;174:104661. doi: 10.1016/j.antiviral.2019.104661. Epub, 2019 Nov 23. PMID:31765674[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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