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Dorssers L, van der Krol S, van der Meer J, van Kammen A, Zabel P. Purification of cowpea mosaic virus RNA replication complex: Identification of a virus-encoded 110,000-dalton polypeptide responsible for RNA chain elongation. Proc Natl Acad Sci U S A 2010; 81:1951-5. [PMID: 16593443 PMCID: PMC345414 DOI: 10.1073/pnas.81.7.1951] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
An endogenous cowpea mosaic virus (CPMV) RNA-protein complex (CPMV replication complex) capable of elongating in vitro preexisting nascent chains to full-length viral RNAs has been solubilized from the membrane fraction of CPMV-infected cowpea leaves using Triton X-100 and purified by Sepharose 2B chromatography and glycerol gradient centrifugation in the presence of Triton X-100. Analysis of the polypeptide composition of the complex by NaDod-SO(4)/PAGE and silver staining revealed major polypeptides with molecular masses of 110, 68, and 57 kilodaltons (kDa), among which the 110-kDa polypeptide was consistently found to cosediment precisely with the RNA polymerase activity. Using antisera to specific viral proteins, we found the 110-kDa polypeptide to be the only known viral polypeptide associated with the RNA replication complex, the 68- and 57-kDa polypeptides being most probably host-specific. The host-encoded 130-kDa monomeric RNA-dependent RNA polymerase, which is known to be stimulated in CPMV-infected cowpea leaves, did not copurify with the virus-specific RNA polymerase complex. Our results dispute the hypothesis that plant viral RNA replication may be mediated by the RNA-dependent RNA polymerase of uninfected plants. We tentatively conclude that the 110-kDa polypeptide encoded by the bottom component RNA of CPMV constitutes the core of the CPMV RNA replication complex.
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Affiliation(s)
- L Dorssers
- Department of Molecular Biology, Agricultural University, De Dreijen 11, 6703 BC Wageningen, The Netherlands
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Franssen H, Moerman M, Rezelman G, Goldbach R. Evidence That the 32,000-Dalton Protein Encoded by Bottom-Component RNA of Cowpea Mosaic Virus is a Proteolytic Processing Enzyme. J Virol 2010; 50:183-90. [PMID: 16789248 PMCID: PMC255598 DOI: 10.1128/jvi.50.1.183-190.1984] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Translation of middle-component RNA of cowpea mosaic virus in vitro produced two polypeptides of 95 and 105 kilodaltons (95K and 105K, respectively) with overlapping amino acid sequences, which were specifically cleaved by a protease encoded by the bottom-component RNA. The proteolytic cleavage was studied by the addition of antibodies raised against various bottom-component RNA-encoded proteins to extracts prepared from bottom-component RNA-inoculated cowpea protoplasts. Since antiserum to the 32K polypeptide efficiently inhibited the proteolytic activity of such extracts, although antiserum to VPg or to the 170K polypeptide did not, evidence was obtained which indicates that the 32K polypeptide represents the protease involved. Fractionation of proteolytically active extract by glycerol gradient centrifugation demonstrated that 32K polypeptides do not exist as free proteins but are aggregated to the bottom-component RNA-encoded 170K, 84K, 60K, or 58K polypeptides. Maximal proteolytic activity was observed for 32K polypeptides associated with 170K polypeptides, suggesting that the activity was unstable and confined to newly synthesized molecules.
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Affiliation(s)
- H Franssen
- Department of Molecular Biology, Agricultural University, 6703 BC Wageningen, The Netherlands
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de Mejia MV, Hiebert E, Purcifull DE, Thornbury DW, Pirone TP. Identification of potyviral amorphous inclusion protein as a nonstructural, virus-specific protein related to helper component. Virology 2008; 142:34-43. [PMID: 18639843 DOI: 10.1016/0042-6822(85)90420-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/1984] [Accepted: 11/14/1984] [Indexed: 11/30/2022]
Abstract
Antisera to amorphous inclusion (AI) proteins associated with infections by pepper mottle virus (PeMV) and the watermelon mosaic virus-1 strain of papaya ringspot virus (PRSV-W) were used to probe in vitro translation products of the viral RNAs. The major translation product of PeMV RNA in the rabbit reticulocyte lysate (RRL) system was a previously reported polypeptide of apparent molecular weight 78,000 (Mr 78K). It reacted with anti-AI serum, whereas the major translation product in the wheat germ (WG) system was a 30K polypeptide that did not react with the antiserum. These results, the Mr values, and analyses of peptides generated by partial digestion with proteinase indicate that the amino acid sequences of the 30K polypeptide and the (Mr) 51K AI protein are distinct subsets of the 78K polypeptide amino acid sequence. Similar results were obtained with PRSV-W except that the Mr values of the corresponding translation products are 110K (RRL) and 60K (WG). Thus the 5'-most region of the PeMV and PRSV-W RNAs (corresponding to 78K and 110K, respectively) appears to encode two proteins rather than one as previously supposed on the basis of RRL translation products. Reciprocal serological tests revealed that the tobacco vein mottling virus aphid transmission helper component protein was related to AI protein. There is direct evidence that the AI represent another potyviral-coded nonstructural protein and the first evidence that a biologically functional protein is related to a component of a potyviral inclusion.
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Affiliation(s)
- M V de Mejia
- Plant Pathology Department, University of Florida, Gainesville, Florida 32611, USA
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Acosta O, Mayo MA. Polypeptide synthesis induced in Nicotiana clevelandii protoplasts by infection with raspberry ringspot nepovirus. Arch Virol 1993; 129:145-54. [PMID: 8470949 DOI: 10.1007/bf01316891] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Infection of Nicotiana clevelandii protoplasts by raspberry ringspot nepovirus resulted in the accumulation of about 24 polypeptides that differed in M(r) and pI from polypeptides accumulating in mock-inoculated protoplasts. Similar polypeptides accumulated in protoplasts infected with the S and E strains of RRV but different infection-specific polypeptides were detected in protoplasts infected with tobacco ringspot nepovirus. The M(r) of RRV-specific polypeptides ranged from 210,000 to 18,000 and most are presumed to be derived from others by proteolytic cleavage. No evidence was found for marked changes in polypeptide abundance with time after inoculation or for any virus-specific polypeptide becoming disproportionately abundant in the medium during culture.
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Affiliation(s)
- O Acosta
- Scottish Crop Research Institute, Invergowrie, Dundee, Scotland
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Peters SA, Voorhorst WG, Wellink J, van Kammen A. Processing of VPg-containing polyproteins encoded by the B-RNA from cowpea mosaic virus. Virology 1992; 191:90-7. [PMID: 1413529 DOI: 10.1016/0042-6822(92)90169-p] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
To study the processing of putative VPg precursors the expression of specific mutant transcripts derived from a full-length cDNA clone of cowpea mosaic virus (CPMV) B-RNA was examined in a rabbit reticulocyte lysate system. This study revealed that the 170K protein produced by a B-RNA mutant that lacks the 32K coding region was efficiently processed by mainly intramolecular cleavages at three different sites into three sets of proteins of 60K + 110K, 84K + 87K, and 58K + 112K. Further cleavage of the 60K protein into 58K and VPg has not been observed in this in vitro system. The 84K protein can be further processed by an intramolecular cleavage reaction via two alternative pathways, either into 26K (VPg + 24K) and 58K proteins or into 24K and 60K proteins. VPg can be released from the 112K (VPg + 110K) precursor either directly or via the 26K intermediate. Immunoblot analysis showed that the 112K protein is present in CPMV-infected plant cells indicating that the in vitro observations may hold true in vivo.
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Affiliation(s)
- S A Peters
- Department of Molecular Biology, Agricultural University, Wageningen, The Netherlands
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Vos P, Jaegle M, Wellink J, Verver J, Eggen R, Van Kammen A, Goldbach R. Infectious RNA transcripts derived from full-length DNA copies of the genomic RNAs of cowpea mosaic virus. Virology 1988; 165:33-41. [PMID: 3388776 DOI: 10.1016/0042-6822(88)90655-1] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
A set of full-length DNA copies of both M and B RNA of cowpea mosaic virus (CPMV) was cloned downstream of a phage T7 promoter. Upon in vitro transcription using T7 RNA polymerase, M and B RNA-like transcripts were obtained from these DNA copies with only two additional nucleotides at the 5' end and five extra nucleotides at the 3' end in comparison to natural viral RNA. In cowpea protoplasts the transcripts of several cDNA clones of B RNA were able to replicate leading to detectable synthesis of viral RNA and proteins. Transcripts of M cDNA clones inoculated together with these B RNA transcripts were also expressed, although the number of protoplasts in which both transcripts were expressed was very low. Preliminary infectivity tests with mutagenized RNA transcripts indicate essential roles of the B RNA-encoded 24K and 32K polypeptides in viral RNA replication.
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Affiliation(s)
- P Vos
- Department of Molecular Biology, Agricultural University, Wageningen, The Netherlands
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Vos P, Verver J, Jaegle M, Wellink J, van Kammen A, Goldbach R. Two viral proteins involved in the proteolytic processing of the cowpea mosaic virus polyproteins. Nucleic Acids Res 1988; 16:1967-85. [PMID: 3282225 PMCID: PMC338193 DOI: 10.1093/nar/16.5.1967] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
A series of specific deletion mutants derived from a full-length cDNA clone of cowpea mosaic virus (CPMV) B RNA was constructed with the aim to study the role of viral proteins in the proteolytic processing of the primary translation products. For the same purpose cDNA clones were constructed having sequences derived from both M and B RNA of CPMV. In vitro transcripts prepared from these clones with T7 RNA polymerase, were efficiently translated in rabbit reticulocyte lysates. The translation products obtained were processed in the lysate by specific proteolytic cleavages into smaller products, which made it possible to study subsequently the effect of the various mutations on this process. The results obtained indicate that the B RNA-encoded 24K polypeptide represents a protease responsible for all cleavages in the polyproteins produced by both CPMV B and M RNA. For efficient cleavage of the glutamine-methionine site in the M RNA encoded polyprotein the presence of a second B RNA encoded protein, the 32K polypeptide, is essential, although the 32K polypeptide itself does not have proteolytic activity. A number of cleavage-site mutants were constructed in which the coding sequence for the glutamine-glycine cleavage site between the two capsid proteins was changed. Subsequent in vitro transcription and translation of these cleavage site mutants show that a correct dipeptide sequence is a prerequisite for efficient cleavage but that the folding of the polypeptide chain also plays an important role in the formation of a cleavage site.
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Affiliation(s)
- P Vos
- Department of Molecular Biology, Agricultural University, Wageningen, The Netherlands
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Wellink J, Jaegle M, Goldbach R. Detection of a Novel Protein Encoded by the Bottom-Component RNA of Cowpea Mosaic Virus, Using Antibodies Raised against a Synthetic Peptide. J Virol 1987; 61:236-8. [PMID: 16789262 PMCID: PMC255253 DOI: 10.1128/jvi.61.1.236-238.1987] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A peptide was synthesized that corresponded to a sequence in the cowpea mosaic virus bottom-component RNA-encoded 200-kilodalton polyprotein showing homology to the picornaviral 3C proteases. By injecting a rabbit with this peptide, antibodies were obtained that allowed the detection of a novel viral protein derived from the 200-kilodalton polyprotein. This protein, which had a size of 24 kilodaltons was found in both infected cowpea leaves and cowpea protoplasts.
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Affiliation(s)
- J Wellink
- Department of Molecular Biology, Agricultural University, De Dreyen 11, 6703 BC Wageningen, The Netherlands
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Wellink J, Rezelman G, Goldbach R, Beyreuther K. Determination of the Proteolytic Processing Sites in the Polyprotein Encoded by the Bottom-Component RNA of Cowpea Mosaic Virus. J Virol 1986; 59:50-8. [PMID: 16789257 PMCID: PMC253037 DOI: 10.1128/jvi.59.1.50-58.1986] [Citation(s) in RCA: 58] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The bottom-component RNA (B-RNA) of cowpea mosaic virus is expressed by the production of a ∼200,000-dalton polyprotein (200K polyprotein), from which the functional proteins are formed by specific proteolytic cleavages. Partial amino-terminal sequences of the various B-RNA-encoded proteins have now been determined. Comparison of the information obtained with the B-RNA sequence allowed the localization of the coding regions for these proteins on B-RNA, the calculation of their precise molecular weights, and the determination of the cleavage sites at which they are released from the polyprotein precursor. Sequence analysis of the 32K protein, which is derived from the amino-terminal end of the 200K polyprotein, indicated that the AUG codon at nucleotide position 207 of the RNA sequence is the translation initiation codon. Sequence analysis of the 170K, 110K, 87K, 84K, 60K, and 58K proteins revealed the existence of three types of cleavage site in the 200K polyprotein: glutamine-serine (two sites), glutamine-methionine (one site), and glutamine-glycine (one site) amino acid pairs. The nature of these cleavage sites suggested that two different viral proteases are involved in the processing of the B-RNA-encoded polyprotein.
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Affiliation(s)
- J Wellink
- Department of Molecular Biology, Agricultural University, 6703 BC Wageningen, The Netherlands
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Argos P, Kamer G, Nicklin MJ, Wimmer E. Similarity in gene organization and homology between proteins of animal picornaviruses and a plant comovirus suggest common ancestry of these virus families. Nucleic Acids Res 1984; 12:7251-67. [PMID: 6384934 PMCID: PMC320155 DOI: 10.1093/nar/12.18.7251] [Citation(s) in RCA: 203] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The amino acid sequences deduced from the nucleic acid sequences of several animal picornaviruses and cowpea mosaic virus (CPMV), a plant virus, were compared. Good homology was found between CPMV and the picornaviruses in the region of the picornavirus 2C (P2-X protein), VPg, 3C pro (proteinase) and 3D pol (RNA polymerase) regions. The CPMV B genome was found to have a similar gene organization to the picornaviruses. A comparison of the 3C pro (proteinase) regions of all of the available picornavirus sequences and CPMV allowed us to identify residues that are completely conserved; of these only two residues, Cys-147 and His-161 (poliovirus proteinase) could be the reactive residues of the active site of a proteinase with analogous mechanism to a known proteinase. We conclude that the proteinases encoded by these viruses are probably cysteine proteinases, mechanistically related, but not homologous to papain.
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Franssen H, Leunissen J, Goldbach R, Lomonossoff G, Zimmern D. Homologous sequences in non-structural proteins from cowpea mosaic virus and picornaviruses. EMBO J 1984; 3:855-61. [PMID: 16453518 PMCID: PMC557438 DOI: 10.1002/j.1460-2075.1984.tb01896.x] [Citation(s) in RCA: 103] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Computer analyses have revealed sequence homology between two non-structural proteins encoded by cowpea mosaic virus (CPMV), and corresponding proteins encoded by two picornaviruses, poliovirus and foot-and-mouth disease virus. A region of 535 amino acids in the 87-K polypeptide from CPMV was found to be homologous to the RNA-dependent RNA polymerases from both picornaviruses, the best matches being found where the picornaviral proteins most resemble each other. Additionally, the 58-K polypeptide from CPMV and polypeptide P2-X from poliovirus contain a conserved region of 143 amino acids. Based on the homology observed, a genetic map of the CPMV genome has been constructed in which the 87-K polypeptide represents the core polymerase domain of the CPMV replicase. These results have implications for the evolution of RNA viruses, and mechanisms are discussed which may explain the existence of homology between picornaviruses (animal viruses with single genomic RNAs) and comoviruses (plant viruses with two genomic RNAs).
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Affiliation(s)
- H Franssen
- Department of Molecular Biology, Agricultural University, De Dreijen 11, 6703 BC Wageningen
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Daubert SD, Bruening G. Detection of Genome-Linked Proteins of Plant and Animal Viruses. ACTA ACUST UNITED AC 1984. [DOI: 10.1016/b978-0-12-470208-0.50015-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
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The RNA-dependent RNA polymerase of cowpea is not involved in cowpea mosaic virus RNA replication: Immunological evidence. Virology 1984; 132:413-25. [DOI: 10.1016/0042-6822(84)90046-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/1983] [Accepted: 09/22/1985] [Indexed: 11/19/2022]
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Strauss EG, Strauss JH. Replication strategies of the single stranded RNA viruses of eukaryotes. Curr Top Microbiol Immunol 1983; 105:1-98. [PMID: 6354610 DOI: 10.1007/978-3-642-69159-1_1] [Citation(s) in RCA: 66] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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