Proteinase 3C-mediated processing of VP1-2A of two hepatitis A virus strains: in vivo evidence for cleavage at amino acid position 273/274 of VP1.
Two prominent features distinguish hepatitis A virus (HAV) from other members of the picornavirus family. A C-terminally prolonged precursor of the structural protein VP1 is incorporated into assembly intermediates (e.g., the provirion), and a single proteinase is contained within the HAV polyprotein. Using an in vivo expression system, we show that proteolytic liberation of VP1 from its precursors P1-2A and VP1-2A is catalyzed by the virus-encoded proteinase 3Cpro. Among the proposed cleavage sites within VP1-2A, the Glu/Ser pair found at VP1 amino acid position 273/274 of most HAV strains is efficiently processed, whereas proteolysis of the Val/Ser site of the attenuated HM175 strain is protracted. Two mutations within VP1-2A (Lys[297]Arg and Ser[330]Asn) had no effect on 3Cpro-mediated cleavage at this site. Additional sites in this region of VP1-2A can also be utilized as substrates by the proteinase, yet less efficiently, and might give rise to smaller and larger VP1 polypeptides also detected in HAV-infected cells.
Probst
C
C
Institute for Medical Molecular Biology, Medical University of Lübeck,Germany.
Jecht
M
M
Gauss-Müller
V
V
D000086042:3C Viral Proteases; D000595:Amino Acid Sequence; D001665:Binding Sites; D003001:Cloning, Molecular; D003546:Cysteine Endopeptidases / Q000235:genetics / Q000378:metabolism*; D006507:Hepatovirus / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D010957:Plasmids; D011498:Protein Precursors / Q000235:genetics / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D014764:Viral Proteins; D015678:Viral Structural Proteins / Q000235:genetics / Q000378:metabolism*
D011498:Protein Precursors; C096539:VP1 protein, hepatitis A virus; D014764:Viral Proteins; D015678:Viral Structural Proteins; D003546:Cysteine Endopeptidases; D000086042:3C Viral Proteases; C057400:picornain 2A, Picornavirus