7mia
Maize rayado fino virus protease
Structural highlights
FunctionPOLG_MRFVC RNA replication protein replicates the viral genomic RNA. The central part of this protein possibly functions as an ATP-binding helicase and/or methyltransferase (Probable).[1] Capsid protein CP1 and CP2 assemble to form an icosahedral capsid, about 30 nm in diameter, and consisting of capsid proteins CP1 and CP2 in a 1:3 ratio. The capsid encapsulates the single-stranded RNA genome. While CP1 is produced as a C-terminal fusion of the replication protein, CP2 may be expressed from a 3'-co-terminal subgenomic RNA.[2] Publication Abstract from PubMedMarafiviruses are capable of persistent infection in a range of plants that have importance to the agriculture and biofuel industries. Although the genomes of a few of these viruses have been studied in-depth, the composition and processing of the polyproteins produced from their main open reading frames have not. The marafivirus polyprotein consists of essential proteins that form the viral replicase, as well as structural proteins for virus assembly. It has been proposed that marafiviruses code for cysteine proteases within their polyproteins, which act as endopeptidases to autocatalytically cleave the polyprotein into functional domains. Further, it has also been suggested that marafivirus endopeptidases may have deubiquitinating activity, which has been shown to enhance viral replication by downregulating viral protein degradation by the ubiquitin proteasomal pathway as well as tampering with cell signaling associated with innate antiviral responses in other +ssRNA viruses. Here we provide the first evidence of cysteine proteases from six different marafiviruses that harbour deubiquitinating activity and reveal intra-genus differences towards ubiquitin linkage types. We also examine the structural basis of the endopeptidase/deubiquitinase from the marafivirus type member, Maize rayado fino virus. Structures of the enzyme alone and bound to ubiquitin reveal marked structural rearrangements that occur upon binding of Ub and provide insights into substrate specificity and differences that set it apart from other viral cysteine proteases. The endopeptidase of the maize-affecting marafivirus type member Maize rayado fino virus doubles as a deubiquitinase.,Patel A, McBride JAM, Mark BL J Biol Chem. 2021 Jul 12:100957. doi: 10.1016/j.jbc.2021.100957. PMID:34265303[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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