title: Inhibition of the protease activity of influenza virus RNA polymerase PA subunit by viral matrix protein.
abstract: Influenza virus PA is a subunit of RNA-dependent RNA polymerase. We demonstrated that PA has a unique chymotrypsin-like serine protease activity with Ser624 as an active site. To obtain further insight into the role of the protease activity of PA in viral proliferation, we examined the interaction between PA and matrix protein (M1). Both M1 purified from virion and hexa-histidine-tagged M1 expressed in Escherichia coli bound to PA. Hexa-histidine-tagged M1 pulled down PA. The interaction of PA with M1 was sensitive to ionic strength, suggesting that the interaction is formed by electrostatic force. Using Suc-Leu-Leu-Val-Tyr-MCA, a specific substrate for PA protease, M1 was demonstrated to inhibit the amidolytic activity of PA, whereas M1 did not inhibit that of chymotrypsin or trypsin at all. These results suggest that M1 binds to and inhibits the amidolytic activity of PA.
authors.affiliation: Department of Virology, Kurume University School of Medicine, Kurume, Fukuoka 830-0011, Japan.
authors.forename: Koyu
authors.initials: K
authors.lastname: Hara
authors.forename: Mayumi
authors.initials: M
authors.lastname: Shiota
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kido
authors.forename: Ken
authors.initials: K
authors.lastname: Watanabe
authors.forename: Kyosuke
authors.initials: K
authors.lastname: Nagata
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Toyoda
mesh_terms: D000818:Animals; D026481:Blotting, Far-Western; D002460:Cell Line; D046508:Culture Techniques; D009980:Influenza A virus; D010447:Peptide Hydrolases / Q000378:metabolism; D011480:Protease Inhibitors / Q000378:metabolism; D011485:Protein Binding; D012324:RNA-Dependent RNA Polymerase / Q000037:antagonists & inhibitors* / Q000302:isolation & purification / Q000378:metabolism*; D011994:Recombinant Proteins / Q000302:isolation & purification / Q000378:metabolism; D018411:Spodoptera; D014763:Viral Matrix Proteins / Q000302:isolation & purification / Q000378:metabolism; D014764:Viral Proteins / Q000037:antagonists & inhibitors* / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: C031540:M-protein, influenza virus; C488936:M1 protein, Influenza A virus; C061290:PA protein, influenza viruses; D011480:Protease Inhibitors; D011994:Recombinant Proteins; D014763:Viral Matrix Proteins; D014764:Viral Proteins; D012324:RNA-Dependent RNA Polymerase; D010447:Peptide Hydrolases