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1.95 A resolution structure of Norovirus 3CL protease in complex with a triazole-based macrocyclic inhibitor
Structural highlights
FunctionPOLG_NVN68 Protein p48 may play a role in viral replication by interacting with host VAPA, a vesicle-associated membrane protein that plays a role in SNARE-mediated vesicle fusion. This interaction may target replication complex to intracellular membranes.[1] [2] NTPase presumably plays a role in replication. Despite having similarities with helicases, does not seem to display any helicase activity.[3] [4] Protein P22 may play a role in targeting replication complex to intracellular membranes.[5] [6] Viral genome-linked protein is covalently linked to the 5'-end of the positive-strand, negative-strand genomic RNAs and subgenomic RNA. Acts as a genome-linked replication primer. May recruit ribosome to viral RNA thereby promoting viral proteins translation.[7] [8] 3C-like protease processes the polyprotein: 3CLpro-RdRp is first released by autocleavage, then all other proteins are cleaved. May cleave host polyadenylate-binding protein thereby inhibiting cellular translation (By similarity).[9] [10] RNA-directed RNA polymerase replicates genomic and antigenomic RNA by recognizing replications specific signals. Transcribes also a subgenomic mRNA by initiating RNA synthesis internally on antigenomic RNA. This sgRNA encodes for structural proteins. Catalyzes the covalent attachment VPg with viral RNAs (By similarity).[11] [12] Publication Abstract from PubMedHuman noroviruses are the primary cause of outbreaks of acute gastroenteritis worldwide. The problem is further compounded by the current lack of norovirus-specific antivirals or vaccines. Noroviruses have a single-stranded, positive sense 7 to 8 kb RNA genome which encodes a polyprotein precursor that is processed by a virus-encoded 3C-like cysteine protease (NV 3CLpro) to generate at least six mature nonstructural proteins. Processing of the polyprotein is essential for virus replication, consequently, NV 3CLpro has emerged as an attractive target for the discovery of norovirus therapeutics and prophylactics. We have recently described the structure-based design of macrocyclic transition state inhibitors of NV 3CLpro. In order to gain insight and understanding into the interaction of macrocyclic inhibitors with the enzyme, as well as probe the effect of ring size on pharmacological activity and cellular permeability, additional macrocyclic inhibitors were synthesized and high resolution cocrystal structures determined. The results of our studies tentatively suggest that the macrocyclic scaffold may hamper optimal binding to the active site by impeding concerted cross-talk between the S2 and S4 subsites. Putative structural rearrangements associated with the interaction of macrocyclic inhibitors with norovirus 3CL protease.,Galasiti Kankanamalage AC, Weerawarna PM, Rathnayake AD, Kim Y, Mehzabeen N, Battaile KP, Lovell S, Chang KO, Groutas WC Proteins. 2019 Mar 18. doi: 10.1002/prot.25682. PMID:30883881[13] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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