title: The hepatitis E virus open reading frame 3 protein activates ERK through binding and inhibition of the MAPK phosphatase.
abstract: The hepatitis E virus causes acute viral hepatitis endemic in much of the developing world and is a serious public health problem. However, due to the lack of an in vitro culture system or a small animal model, its biology and pathogenesis are poorly understood. We have shown earlier that the ORF3 protein (pORF3) of hepatitis E virus activates ERK, a member of the MAPK superfamily. Here we have explored the mechanism of pORF3-mediated ERK activation and demonstrated it to be independent of the Raf/MEK pathway. Using biochemical assays, yeast two-hybrid analysis, and intracellular fluorescence resonance energy transfer we showed that pORF3 binds Pyst1, a prototypic member of the ERK-specific MAPK phosphatase. The binding regions in the two proteins were mapped to the N terminus of pORF3 and a central portion of Pyst1. Expression of pORF3 protected ERK from the inhibitory effects of ectopically expressed Pyst1. This is the first example of a viral protein regulating ERK activation by inhibition of its cognate dual specificity phosphatase.
authors.affiliation: Virology Group, International Centre for Genetic Engineering and Biotechnology, New Delhi 110067, India.
authors.forename: Anindita
authors.initials: A
authors.lastname: Kar-Roy
authors.forename: Hasan
authors.initials: H
authors.lastname: Korkaya
authors.forename: Ruchi
authors.initials: R
authors.lastname: Oberoi
authors.forename: Sunil Kumar
authors.initials: SK
authors.lastname: Lal
authors.forename: Shahid
authors.initials: S
authors.lastname: Jameel
mesh_terms: D000818:Animals; D015153:Blotting, Western; D019556:COS Cells; D018797:Cell Cycle Proteins; D002460:Cell Line; D003593:Cytoplasm / Q000201:enzymology; D054638:Dual Specificity Phosphatase 1; D054642:Dual Specificity Phosphatase 6; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D031541:Fluorescence Resonance Energy Transfer; D005982:Glutathione Transferase / Q000378:metabolism; D017874:Immediate-Early Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D048031:JNK Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D008954:Models, Biological; D016366:Open Reading Frames; D010749:Phosphoprotein Phosphatases; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism; D010957:Plasmids / Q000378:metabolism; D011233:Precipitin Tests; D011485:Protein Binding; D014176:Protein Biosynthesis; D054645:Protein Phosphatase 1; D017434:Protein Structure, Tertiary; D017027:Protein Tyrosine Phosphatases / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D015398:Signal Transduction; D013997:Time Factors; D014162:Transfection; D020798:Two-Hybrid System Techniques; D014764:Viral Proteins / Q000378:metabolism*
chemical_list: D018797:Cell Cycle Proteins; D004791:Enzyme Inhibitors; D017874:Immediate-Early Proteins; C400973:ORF3 protein, Hepatitis E virus; D014764:Viral Proteins; D005982:Glutathione Transferase; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D020929:Mitogen-Activated Protein Kinase Kinases; D010749:Phosphoprotein Phosphatases; D054645:Protein Phosphatase 1; D010744:Phosphoric Monoester Hydrolases; D054638:Dual Specificity Phosphatase 1; D054642:Dual Specificity Phosphatase 6; D017027:Protein Tyrosine Phosphatases