| Structural highlights
Function
[POLN_SFV] P123 is short-lived polyproteins, accumulating during early stage of infection. It localizes the viral replication complex to the cytoplasmic surface of modified endosomes and lysosomes. By interacting with nsP4, it starts viral genome replication into antigenome. After these early events, P123 is cleaved sequentially into nsP1, nsP2 and nsP3. This sequence of delayed processing would allow correct assembly and membrane association of the RNA polymerase complex.[1] [2] [3] [4] [5] [6] [7] [8] nsP1 is a cytoplasmic capping enzyme. This function is necessary since all viral RNAs are synthesized in the cytoplasm, and host capping enzymes are restricted to the nucleus. The enzymatic reaction involves a covalent link between 7-methyl-GMP and nsP1, whereas eukaryotic capping enzymes form a covalent complex only with GMP. nsP1 capping would consist in the following reactions: GTP is first methylated and then forms the m7GMp-nsP1 complex, from which 7-methyl-GMP complex is transferred to the mRNA to create the cap structure. Palmitoylated nsP1 is remodeling host cell cytoskeleton, and induces filopodium-like structure formation at the surface of the host cell.[9] [10] [11] [12] [13] [14] [15] [16] nsP2 has two separate domain with different biological activities. The N-terminal section is part of the RNA polymerase complex and has RNA trisphosphatase and RNA helicase activity. The C-terminal section harbors a protease that specifically cleaves and releases the four mature proteins. Also inhibits cellular transcription by inducing rapid degradation of POLR2A, a catalytic subunit of the RNAPII complex. The resulting inhibition of cellular protein synthesis serves to ensure maximal viral gene expression and to evade host immune response.[17] [18] [19] [20] [21] [22] [23] [24] nsP3 is essential for minus strand and subgenomic 26S mRNA synthesis.[25] [26] [27] [28] [29] [30] [31] [32] nsP4 is an RNA dependent RNA polymerase. It replicates genomic and antigenomic RNA by recognizing replications specific signals. Transcribes also a 26S subgenomic mRNA by initiating RNA synthesis internally on antigenomic RNA. This 26S mRNA codes for structural proteins.[33] [34] [35] [36] [37] [38] [39] [40]
Publication Abstract from PubMed
The RNA replication complex of Semliki Forest virus is bound to cytoplasmic membranes via the mRNA-capping enzyme Nsp1. Here we have studied the structure and liposome interactions of a synthetic peptide (245)GSTLYTESRKLLRSWHLPSV(264) corresponding to the membrane binding domain of Nsp1. The peptide interacted with liposomes only if negatively charged lipids were present that induced a structural change in the peptide from a random coil to a partially alpha-helical conformation. NMR structure shows that the alpha-helix is amphipathic, the hydrophobic surface consisting of several leucines, a valine, and a tryptophan moiety (Trp-259). Fluorescence studies revealed that this tryptophan intercalates in the bilayer to the depth of the ninth and tenth carbons of lipid acyl chains. Mutation W259A altered the mode of bilayer association of the peptide and abolished its ability to compete for membrane association of intact Nsp1, demonstrating its crucial role in the membrane association and function of Nsp1.
Membrane binding mechanism of an RNA virus-capping enzyme.,Lampio A, Kilpelainen I, Pesonen S, Karhi K, Auvinen P, Somerharju P, Kaariainen L J Biol Chem. 2000 Dec 1;275(48):37853-9. PMID:10984480[41]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
See Also
References
- ↑ Rikkonen M, Peranen J, Kaariainen L. ATPase and GTPase activities associated with Semliki Forest virus nonstructural protein nsP2. J Virol. 1994 Sep;68(9):5804-10. PMID:8057461
- ↑ Ahola T, Kaariainen L. Reaction in alphavirus mRNA capping: formation of a covalent complex of nonstructural protein nsP1 with 7-methyl-GMP. Proc Natl Acad Sci U S A. 1995 Jan 17;92(2):507-11. PMID:7831320
- ↑ Ahola T, Laakkonen P, Vihinen H, Kaariainen L. Critical residues of Semliki Forest virus RNA capping enzyme involved in methyltransferase and guanylyltransferase-like activities. J Virol. 1997 Jan;71(1):392-7. PMID:8985362
- ↑ Laakkonen P, Auvinen P, Kujala P, Kaariainen L. Alphavirus replicase protein NSP1 induces filopodia and rearrangement of actin filaments. J Virol. 1998 Dec;72(12):10265-9. PMID:9811773
- ↑ Gomez de Cedron M, Ehsani N, Mikkola ML, Garcia JA, Kaariainen L. RNA helicase activity of Semliki Forest virus replicase protein NSP2. FEBS Lett. 1999 Apr 1;448(1):19-22. PMID:10217401
- ↑ Vasiljeva L, Merits A, Auvinen P, Kaariainen L. Identification of a novel function of the alphavirus capping apparatus. RNA 5'-triphosphatase activity of Nsp2. J Biol Chem. 2000 Jun 9;275(23):17281-7. PMID:10748213 doi:http://dx.doi.org/10.1074/jbc.M910340199
- ↑ Sawicki DL, Perri S, Polo JM, Sawicki SG. Role for nsP2 proteins in the cessation of alphavirus minus-strand synthesis by host cells. J Virol. 2006 Jan;80(1):360-71. PMID:16352561 doi:http://dx.doi.org/10.1128/JVI.80.1.360-371.2006
- ↑ Akhrymuk I, Kulemzin SV, Frolova EI. Evasion of the innate immune response: the Old World alphavirus nsP2 protein induces rapid degradation of Rpb1, a catalytic subunit of RNA polymerase II. J Virol. 2012 Jul;86(13):7180-91. doi: 10.1128/JVI.00541-12. Epub 2012 Apr 18. PMID:22514352 doi:http://dx.doi.org/10.1128/JVI.00541-12
- ↑ Rikkonen M, Peranen J, Kaariainen L. ATPase and GTPase activities associated with Semliki Forest virus nonstructural protein nsP2. J Virol. 1994 Sep;68(9):5804-10. PMID:8057461
- ↑ Ahola T, Kaariainen L. Reaction in alphavirus mRNA capping: formation of a covalent complex of nonstructural protein nsP1 with 7-methyl-GMP. Proc Natl Acad Sci U S A. 1995 Jan 17;92(2):507-11. PMID:7831320
- ↑ Ahola T, Laakkonen P, Vihinen H, Kaariainen L. Critical residues of Semliki Forest virus RNA capping enzyme involved in methyltransferase and guanylyltransferase-like activities. J Virol. 1997 Jan;71(1):392-7. PMID:8985362
- ↑ Laakkonen P, Auvinen P, Kujala P, Kaariainen L. Alphavirus replicase protein NSP1 induces filopodia and rearrangement of actin filaments. J Virol. 1998 Dec;72(12):10265-9. PMID:9811773
- ↑ Gomez de Cedron M, Ehsani N, Mikkola ML, Garcia JA, Kaariainen L. RNA helicase activity of Semliki Forest virus replicase protein NSP2. FEBS Lett. 1999 Apr 1;448(1):19-22. PMID:10217401
- ↑ Vasiljeva L, Merits A, Auvinen P, Kaariainen L. Identification of a novel function of the alphavirus capping apparatus. RNA 5'-triphosphatase activity of Nsp2. J Biol Chem. 2000 Jun 9;275(23):17281-7. PMID:10748213 doi:http://dx.doi.org/10.1074/jbc.M910340199
- ↑ Sawicki DL, Perri S, Polo JM, Sawicki SG. Role for nsP2 proteins in the cessation of alphavirus minus-strand synthesis by host cells. J Virol. 2006 Jan;80(1):360-71. PMID:16352561 doi:http://dx.doi.org/10.1128/JVI.80.1.360-371.2006
- ↑ Akhrymuk I, Kulemzin SV, Frolova EI. Evasion of the innate immune response: the Old World alphavirus nsP2 protein induces rapid degradation of Rpb1, a catalytic subunit of RNA polymerase II. J Virol. 2012 Jul;86(13):7180-91. doi: 10.1128/JVI.00541-12. Epub 2012 Apr 18. PMID:22514352 doi:http://dx.doi.org/10.1128/JVI.00541-12
- ↑ Rikkonen M, Peranen J, Kaariainen L. ATPase and GTPase activities associated with Semliki Forest virus nonstructural protein nsP2. J Virol. 1994 Sep;68(9):5804-10. PMID:8057461
- ↑ Ahola T, Kaariainen L. Reaction in alphavirus mRNA capping: formation of a covalent complex of nonstructural protein nsP1 with 7-methyl-GMP. Proc Natl Acad Sci U S A. 1995 Jan 17;92(2):507-11. PMID:7831320
- ↑ Ahola T, Laakkonen P, Vihinen H, Kaariainen L. Critical residues of Semliki Forest virus RNA capping enzyme involved in methyltransferase and guanylyltransferase-like activities. J Virol. 1997 Jan;71(1):392-7. PMID:8985362
- ↑ Laakkonen P, Auvinen P, Kujala P, Kaariainen L. Alphavirus replicase protein NSP1 induces filopodia and rearrangement of actin filaments. J Virol. 1998 Dec;72(12):10265-9. PMID:9811773
- ↑ Gomez de Cedron M, Ehsani N, Mikkola ML, Garcia JA, Kaariainen L. RNA helicase activity of Semliki Forest virus replicase protein NSP2. FEBS Lett. 1999 Apr 1;448(1):19-22. PMID:10217401
- ↑ Vasiljeva L, Merits A, Auvinen P, Kaariainen L. Identification of a novel function of the alphavirus capping apparatus. RNA 5'-triphosphatase activity of Nsp2. J Biol Chem. 2000 Jun 9;275(23):17281-7. PMID:10748213 doi:http://dx.doi.org/10.1074/jbc.M910340199
- ↑ Sawicki DL, Perri S, Polo JM, Sawicki SG. Role for nsP2 proteins in the cessation of alphavirus minus-strand synthesis by host cells. J Virol. 2006 Jan;80(1):360-71. PMID:16352561 doi:http://dx.doi.org/10.1128/JVI.80.1.360-371.2006
- ↑ Akhrymuk I, Kulemzin SV, Frolova EI. Evasion of the innate immune response: the Old World alphavirus nsP2 protein induces rapid degradation of Rpb1, a catalytic subunit of RNA polymerase II. J Virol. 2012 Jul;86(13):7180-91. doi: 10.1128/JVI.00541-12. Epub 2012 Apr 18. PMID:22514352 doi:http://dx.doi.org/10.1128/JVI.00541-12
- ↑ Rikkonen M, Peranen J, Kaariainen L. ATPase and GTPase activities associated with Semliki Forest virus nonstructural protein nsP2. J Virol. 1994 Sep;68(9):5804-10. PMID:8057461
- ↑ Ahola T, Kaariainen L. Reaction in alphavirus mRNA capping: formation of a covalent complex of nonstructural protein nsP1 with 7-methyl-GMP. Proc Natl Acad Sci U S A. 1995 Jan 17;92(2):507-11. PMID:7831320
- ↑ Ahola T, Laakkonen P, Vihinen H, Kaariainen L. Critical residues of Semliki Forest virus RNA capping enzyme involved in methyltransferase and guanylyltransferase-like activities. J Virol. 1997 Jan;71(1):392-7. PMID:8985362
- ↑ Laakkonen P, Auvinen P, Kujala P, Kaariainen L. Alphavirus replicase protein NSP1 induces filopodia and rearrangement of actin filaments. J Virol. 1998 Dec;72(12):10265-9. PMID:9811773
- ↑ Gomez de Cedron M, Ehsani N, Mikkola ML, Garcia JA, Kaariainen L. RNA helicase activity of Semliki Forest virus replicase protein NSP2. FEBS Lett. 1999 Apr 1;448(1):19-22. PMID:10217401
- ↑ Vasiljeva L, Merits A, Auvinen P, Kaariainen L. Identification of a novel function of the alphavirus capping apparatus. RNA 5'-triphosphatase activity of Nsp2. J Biol Chem. 2000 Jun 9;275(23):17281-7. PMID:10748213 doi:http://dx.doi.org/10.1074/jbc.M910340199
- ↑ Sawicki DL, Perri S, Polo JM, Sawicki SG. Role for nsP2 proteins in the cessation of alphavirus minus-strand synthesis by host cells. J Virol. 2006 Jan;80(1):360-71. PMID:16352561 doi:http://dx.doi.org/10.1128/JVI.80.1.360-371.2006
- ↑ Akhrymuk I, Kulemzin SV, Frolova EI. Evasion of the innate immune response: the Old World alphavirus nsP2 protein induces rapid degradation of Rpb1, a catalytic subunit of RNA polymerase II. J Virol. 2012 Jul;86(13):7180-91. doi: 10.1128/JVI.00541-12. Epub 2012 Apr 18. PMID:22514352 doi:http://dx.doi.org/10.1128/JVI.00541-12
- ↑ Rikkonen M, Peranen J, Kaariainen L. ATPase and GTPase activities associated with Semliki Forest virus nonstructural protein nsP2. J Virol. 1994 Sep;68(9):5804-10. PMID:8057461
- ↑ Ahola T, Kaariainen L. Reaction in alphavirus mRNA capping: formation of a covalent complex of nonstructural protein nsP1 with 7-methyl-GMP. Proc Natl Acad Sci U S A. 1995 Jan 17;92(2):507-11. PMID:7831320
- ↑ Ahola T, Laakkonen P, Vihinen H, Kaariainen L. Critical residues of Semliki Forest virus RNA capping enzyme involved in methyltransferase and guanylyltransferase-like activities. J Virol. 1997 Jan;71(1):392-7. PMID:8985362
- ↑ Laakkonen P, Auvinen P, Kujala P, Kaariainen L. Alphavirus replicase protein NSP1 induces filopodia and rearrangement of actin filaments. J Virol. 1998 Dec;72(12):10265-9. PMID:9811773
- ↑ Gomez de Cedron M, Ehsani N, Mikkola ML, Garcia JA, Kaariainen L. RNA helicase activity of Semliki Forest virus replicase protein NSP2. FEBS Lett. 1999 Apr 1;448(1):19-22. PMID:10217401
- ↑ Vasiljeva L, Merits A, Auvinen P, Kaariainen L. Identification of a novel function of the alphavirus capping apparatus. RNA 5'-triphosphatase activity of Nsp2. J Biol Chem. 2000 Jun 9;275(23):17281-7. PMID:10748213 doi:http://dx.doi.org/10.1074/jbc.M910340199
- ↑ Sawicki DL, Perri S, Polo JM, Sawicki SG. Role for nsP2 proteins in the cessation of alphavirus minus-strand synthesis by host cells. J Virol. 2006 Jan;80(1):360-71. PMID:16352561 doi:http://dx.doi.org/10.1128/JVI.80.1.360-371.2006
- ↑ Akhrymuk I, Kulemzin SV, Frolova EI. Evasion of the innate immune response: the Old World alphavirus nsP2 protein induces rapid degradation of Rpb1, a catalytic subunit of RNA polymerase II. J Virol. 2012 Jul;86(13):7180-91. doi: 10.1128/JVI.00541-12. Epub 2012 Apr 18. PMID:22514352 doi:http://dx.doi.org/10.1128/JVI.00541-12
- ↑ Lampio A, Kilpelainen I, Pesonen S, Karhi K, Auvinen P, Somerharju P, Kaariainen L. Membrane binding mechanism of an RNA virus-capping enzyme. J Biol Chem. 2000 Dec 1;275(48):37853-9. PMID:10984480 doi:10.1074/jbc.M004865200
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