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Publication Abstract from PubMed

Sobemoviruses encode serine-like 3C proteases (Pro) that participate in the processing and maturation of other virus-encoded proteins. Its cis and trans activity is mediated by the naturally unfolded virus-genome-linked protein (VPg). Nuclear magnetic resonance studies show a Pro-VPg complex interaction and VPg tertiary structure; however, information regarding structural changes of the Pro-VPg complex during interaction is lacking. Here, we solved a full Pro-VPg 3D structure of ryegrass mottle virus (RGMoV) that demonstrates the structural changes in three different conformations due to VPg interaction with Pro. We identified a unique site of VPg interaction with Pro that was not observed in other sobemoviruses, and observed different conformations of the Pro beta2 barrel. This is the first report of a full plant Pro crystal structure with its VPg cofactor. We also confirmed the existence of an unusual previously unmapped cleavage site for sobemovirus Pro in the transmembrane domain: E/A. We demonstrated that RGMoV Pro in cis activity is not regulated by VPg and that in trans, VPg can also mediate Pro in free form. Additionally, we observed Ca(2+) and Zn(2+) inhibitory effects on the Pro cleavage activity.

VPg Impact on Ryegrass Mottle Virus Serine-like 3C Protease Proteolysis and Structure.,Kalnins G, Ludviga R, Kalnciema I, Resevica G, Zeltina V, Bogans J, Tars K, Zeltins A, Balke I Int J Mol Sci. 2023 Mar 10;24(6):5347. doi: 10.3390/ijms24065347. PMID:36982419^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.