Influenza virus RNA polymerase PA subunit is a novel serine protease with Ser624 at the active site.
BACKGROUND
Influenza virus RNA polymerase is a multifunctional enzyme that catalyses both transcription and replication of the RNA genome. The function of the influenza virus RNA polymerase PA subunit in viral replication is poorly understood, although the enzyme is known to be required for cRNA --> vRNA synthesis. The protease related activity of PA has been discussed ever since protease-inducing activity was demonstrated in transfection experiments.


RESULTS
PA protein was highly purified from insect cells infected with the recombinant baculovirus carrying PA cDNA, and a novel chymotrypsin-type serine protease activity was identified with the synthetic peptide, Suc-LLVY-MCA, in the PA protein. [3H]DFP was crosslinked with PA and a mutational analysis revealed that serine624 was as an active site for the protease activity.


CONCLUSIONS
These results constitute the demonstration of protease activity in PA subunit of the influenza virus RNA polymerase complexes.
Departments of Virology, Kurume University School of Medicine, Kurume 830-0011, Japan.
K
K
Hara
M
M
Shiota
H
H
Kido
Y
Y
Ohtsu
T
T
Kashiwagi
J
J
Iwahashi
N
N
Hamada
K
K
Mizoue
N
N
Tsumura
H
H
Kato
T
T
Toyoda
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002384:Catalysis; D002853:Chromatography, Liquid; D017931:DNA Primers; D012321:DNA-Directed RNA Polymerases / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D009975:Orthomyxoviridae / Q000201:enzymology*; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D012694:Serine / Q000378:metabolism*; D012697:Serine Endopeptidases / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D018411:Spodoptera
D017931:DNA Primers; D011994:Recombinant Proteins; D012694:Serine; D012321:DNA-Directed RNA Polymerases; D012697:Serine Endopeptidases