F
IPR016269

RNA-directed RNA polymerase, paramyxovirus

InterPro entry
Short nameRNA-dir_pol_paramyxovirus

Description

RNA-directed RNA polymerase (RdRp) (
2.7.7.48
) is an essential protein encoded in the genomes of all RNA containing viruses with no DNA stage
[2, 3]
. It catalyses synthesis of the RNA strand complementary to a given RNA template, but the precise molecular mechanism remains unclear. The postulated RNA replication process is a two-step mechanism. First, the initiation step of RNA synthesis begins at or near the 3' end of the RNA template by means of a primer-independent (de novo) mechanism. The de novo initiation consists in the addition of a nucleotide tri-phosphate (NTP) to the 3'-OH of the first initiating NTP. During the following so-called elongation phase, this nucleotidyl transfer reaction is repeated with subsequent NTPs to generate the complementary RNA product
[4]
.

This entry represents RNA-directed RNA polymerase (also known as the large structural protein) from Mononegavirales including Paramyxoviruses
[1]
. The large structural protein (or L protein) carries four enzymatic activities: RNA-directed RNA polymerase (
2.7.7.48
), mRNA (guanine-N(7)-)-methyltransferase (
2.1.1.56
), mRNA guanylyltransferase (
2.7.7
), and poly(A) synthetase. The viral mRNA guanylyl transferase displays a different biochemical reaction than the cellular enzyme. The template is composed of the viral RNA tightly encapsidated by the nucleoprotein (N). The protein can function either as transcriptase or as replicase. The transcriptase synthesises subsequently subgenomic RNAs, assuring their capping and polyadenylation by a stuttering mechanism. The transcriptase stutters on a specific sequence, resulting on a cotranscriptional editing of the phosphoprotein (P) mRNA. The replicase mode is dependent on intracellular N protein concentration. In this mode, the polymerase replicates the whole viral genome without recognizing the transcriptional signals. 5' GpppApGpG sequence is required for mRNA cap methylation by the enzyme.

References

1.RNA-dependent RNA polymerase gene analysis of worldwide Newcastle disease virus isolates representing different virulence types and their phylogenetic relationship with other members of the paramyxoviridae. Wise MG, Sellers HS, Alvarez R, Seal BS. Virus Res. 104, 71-80, (2004). View articlePMID: 15177894

2.Tentative identification of RNA-dependent RNA polymerases of dsRNA viruses and their relationship to positive strand RNA viral polymerases. Koonin EV, Gorbalenya AE, Chumakov KM. FEBS Lett. 252, 42-6, (1989). View articlePMID: 2759231

3.A reevaluation of the higher taxonomy of viruses based on RNA polymerases. Zanotto PM, Gibbs MJ, Gould EA, Holmes EC. J. Virol. 70, 6083-96, (1996). View articlePMID: 8709232

4.De novo initiation of viral RNA-dependent RNA synthesis. Kao CC, Singh P, Ecker DJ. Virology 287, 251-60, (2001). View articlePMID: 11531403

Further reading

5. Structure of the RNA-dependent RNA polymerase of poliovirus. Hansen JL, Long AM, Schultz SC. Structure 5, 1109-22, (1997). View articlePMID: 9309225

6. Poliovirus RNA-dependent RNA polymerase (3Dpol): structural, biochemical, and biological analysis of conserved structural motifs A and B. Gohara DW, Crotty S, Arnold JJ, Yoder JD, Andino R, Cameron CE. J. Biol. Chem. 275, 25523-32, (2000). View articlePMID: 10827187

7. Analysis of RNA-dependent RNA polymerase structure and function as guided by known polymerase structures and computer predictions of secondary structure. O'Reilly EK, Kao CC. Virology 252, 287-303, (1998). View articlePMID: 9878607

GO terms

Cross References

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