Giuseppe
Emeritus
J Virol. 2008 Oct 22. [Epub ahead of print]
Interaction of the influenza A virus nucleocapsid protein with the viral RNA polymerase potentiates unprimed viral RNA replication.
Newcomb LL, Kuo RL, Ye Q, Jiang Y, Tao YJ, Krug RM. - Institute for Cellular and Molecular Biology, Section of Molecular Genetics and Microbiology, University of Texas at Austin, Austin, Texas 78712 USA; Department of Biochemistry and Cell Biology, Rice University, Houston, Texas 77005 USA.
The influenza A virus polymerase transcribes and replicates the eight virion RNA (vRNA) segments.
Transcription is initiated with capped RNA primers excised from cellular pre-mRNAs by the intrinsic endonuclease of the viral polymerase.
Viral RNA replication occurs in two steps: first a full-length copy of vRNA is made, termed complementary RNA (cRNA), and then this cRNA is copied to produce vRNA.
The synthesis of cRNAs and vRNAs is initiated without a primer, in contrast to the initiation of viral mRNA synthesis, and requires the viral nucleocapsid protein (NP).
The mechanism of unprimed viral RNA replication is poorly understood.
To elucidate this mechanism, we used purified recombinant influenza viral polymerase complexes and NP to establish an in vitro system that catalyzes the unprimed synthesis of cRNA and vRNA using 50-nucleotide-long RNA templates.
The purified viral polymerase and NP are sufficient for catalyzing this RNA synthesis without a primer, suggesting that host cell factors are not required.
We used this purified in vitro replication system to demonstrate that the RNA-binding activity of NP is not required for the unprimed synthesis of cRNA and vRNA.
This result rules out two models that postulate that the RNA-binding activity of NP mediates the switch from capped RNA-primed transcription to unprimed viral RNA replication.
Because we showed that NP lacking RNA-binding activity binds directly to the viral polymerase, it is likely that a direct interaction between NP and the viral polymerase results in a modification of the polymerase in favor of unprimed initiation.
PMID: 18945782 [PubMed - as supplied by publisher
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Interaction of the influenza A virus nucleocapsid protein with the viral RNA polymerase potentiates unprimed viral RNA replication.
Newcomb LL, Kuo RL, Ye Q, Jiang Y, Tao YJ, Krug RM. - Institute for Cellular and Molecular Biology, Section of Molecular Genetics and Microbiology, University of Texas at Austin, Austin, Texas 78712 USA; Department of Biochemistry and Cell Biology, Rice University, Houston, Texas 77005 USA.
The influenza A virus polymerase transcribes and replicates the eight virion RNA (vRNA) segments.
Transcription is initiated with capped RNA primers excised from cellular pre-mRNAs by the intrinsic endonuclease of the viral polymerase.
Viral RNA replication occurs in two steps: first a full-length copy of vRNA is made, termed complementary RNA (cRNA), and then this cRNA is copied to produce vRNA.
The synthesis of cRNAs and vRNAs is initiated without a primer, in contrast to the initiation of viral mRNA synthesis, and requires the viral nucleocapsid protein (NP).
The mechanism of unprimed viral RNA replication is poorly understood.
To elucidate this mechanism, we used purified recombinant influenza viral polymerase complexes and NP to establish an in vitro system that catalyzes the unprimed synthesis of cRNA and vRNA using 50-nucleotide-long RNA templates.
The purified viral polymerase and NP are sufficient for catalyzing this RNA synthesis without a primer, suggesting that host cell factors are not required.
We used this purified in vitro replication system to demonstrate that the RNA-binding activity of NP is not required for the unprimed synthesis of cRNA and vRNA.
This result rules out two models that postulate that the RNA-binding activity of NP mediates the switch from capped RNA-primed transcription to unprimed viral RNA replication.
Because we showed that NP lacking RNA-binding activity binds directly to the viral polymerase, it is likely that a direct interaction between NP and the viral polymerase results in a modification of the polymerase in favor of unprimed initiation.
PMID: 18945782 [PubMed - as supplied by publisher
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