A cellular cofactor facilitates efficient 3CD cleavage of the poliovirus P1 precursor.
The production of poliovirus capsid proteins from a capsid protein precursor (P1) is mediated by virus-encoded proteinase 3CD and involves a complicated set of proteinase-substrate interactions. In addition to substrate and enzymatic determinants required for this interaction, we describe a cellular cofactor, which facilitates 3CD recognition of the P1 precursor. Cellular cofactor activity is 3CD dependent and salt dependent. Our analysis shows that proteolytic cleavage of the P1 precursor at the VP0/VP3 cleavage site exhibits a greater dependency on the cellular cofactor than cleavage at the VP3/VP1 site. Such a greater dependency on cellular cofactor activity can be relieved (in part) by the substitution of an Ala residue for the Pro residue at the -4 position of the VP0/VP3 cleavage site. However, mutant viruses containing Pro-to-Ala substitutions at the -4 position of the VP0/VP3 site exhibit defects in viral growth.
Department of Microbiology and Molecular Genetics, College of Medicine, University of California, Irvine 92717-4025.
W S
WS
Blair
X
X
Li
B L
BL
Semler
D000086042:3C Viral Proteases; D000595:Amino Acid Sequence; D002213:Capsid / Q000378:metabolism*; D003001:Cloning, Molecular; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D010450:Endopeptidases / Q000737:chemistry / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D066298:In Vitro Techniques; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D017354:Point Mutation; D017955:Poliovirus / Q000254:growth & development / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D011506:Proteins / Q000378:metabolism; D013329:Structure-Activity Relationship; D013379:Substrate Specificity; D014764:Viral Proteins / Q000378:metabolism
D046911:Macromolecular Substances; D011506:Proteins; D014764:Viral Proteins; D010450:Endopeptidases; D003546:Cysteine Endopeptidases; D000086042:3C Viral Proteases