Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Polyproteins”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 937 records · Page 52Linked to original sources
PubMed1994

Replication of echo virus type 25 JV-4 reference strain and wild type strains in MRC5 cells compared with that of poliovirus type 1.

In echo virus type 25/JV-4 the shut off of host cell protein synthesis took significantly longer and the kinetics of the synthesis of viral proteins and viral RNA occurred much later than in the poliovirus. However, these characteristics impaired neither polyprotein processing nor virus production in the JV-4 strain. In contrast the two wild strains M.1262 and Th.222 had a lower virus yield than strain JV-4. The presence of a high Mr protein in the pattern of viral proteins of wild strains suggested that a defect in the polyprotein processing was responsible for the decreased virus yield. The infectious cycle of strain Th.222 differed from that of strains JV-4 and M.1262 in the rapid inhibition of host cell translation and the extent of viral protein synthesis. The sensitivity to actinomycin D was also investigated. Strain M.1262 was found to be insensitive. The virus yield of strains JV-4 and Th.222 was three- and fourfold lower respectively in the presence of actinomycin D. This sensitivity to the antibiotic was observed during viral RNA synthesis in strain JV-4 and during viral protein synthesis in strain Th.222. These results suggest that cellular factors are involved in the replication of echo virus type 25 strains in MRC5 cells.

Cell Line↗
PubMed1993

Cloning and nucleotide sequence of the capsid protein and the nuclear inclusion protein (NIb) of potato virus A.

The sequence of the 3'-terminal 2597 nucleotides of potato virus A (PVA) genome has been determined from cDNA clones. An open reading frame was identified and potentially encodes a large polyprotein containing 789 amino acid residues. This large open reading frame was found to have a high similarity to the nuclear inclusion protein (NIb) and the capsid protein (CP) genes of several potyviruses. The data suggest that the PVA NIb and CP are products arising from the maturation of the large polyprotein as observed for other potyviruses. Putative cleavage sites corresponded to consensus sequences NIa/NIb and NIb/CP, respectively, of other potyviruses. The NIb (putative RNA polymerase) and CP are expected to be 516 and 269 amino acid residues (M(r) of 58,939 and 30,094), respectively. The non-coding region is 227 nucleotides long, rich in A and U and unlike other viruses. Furthermore, there are two AUG codons in frame in front of the capsid protein gene suggesting an alternative mode for the capsid protein expression.

Amino Acid Sequence↗
PubMed1994

Sequence analysis of the 3'-terminal half of RNA 1 of wheat spindle streak mosaic virus.

cDNA complementary to the 3'-terminal half of RNA 1 of wheat spindle streak mosaic virus (WSSMV) from Southern France has been cloned and sequenced. One large open reading frame (ORF) of 4410 nucleotides and a nontranslated region (NTR) of 213 nucleotides at the 3'-end excluding the poly(A)-tail were found. Because of the amino acid sequence homology to the polyprotein of barley yellow mosaic virus (BaYMV) RNA 1, the encoded polyprotein of the sequenced region of WSSMV is supposed to comprise the C-terminal part of the putative cytoplasmic inclusion (CI) protein, the nuclear inclusion a (NIa) proteinase, the (NIb) RNA-polymerase and the capsid protein. The first 19 N-terminal amino acids of the capsid protein were determined by direct sequencing of proteins of purified WSSMV particles and confirmed this hypothesis. The deduced capsid protein has 294 amino acids and shows 74% identity with the BaYMV capsid protein sequence. This high sequence homology with BaYMV, in addition to the significant identities with barley mild mosaic virus (BaMMV, 35%) and its marginal homology to capsid protein sequences of aphid and mite-borne potyviruses (22-24%), supports the classification of WSSMV as a distinct member of the genus Baymovirus, family Potyviridae.

Amino Acid Sequence↗
PubMed1994

Expression of recombinant E2 and C proteins of rubella virus in insect cells.

We have constructed a recombinant baculovirus expressing the rubella virus E2 (42-45 KDa) and C (34 KDa) proteins. Sf9 cells infected with recombinant virus were able to synthesize and process the two proteins coded by a unique precursor gene. By immunoblot and immunoprecipitation analysis with polyclonal and monoclonal antibodies, a precursor polyprotein (66 KDa) and two other proteins migrating with an apparent molecular weight of 42 KDa and 36 KDa were recognized as E2 glycoprotein and C protein, respectively. The recombinant E2 protein appeared to be glycosylated since it was susceptible to tunicamycin. The results indicate that the RV polyprotein coding for E2 and C is expressed and proteolytically cleaved in insect cells. This baculovirus expression system provides a useful alternative approach for the production of rubella virus antigens and should allow the purification of large quantities of the RV proteins for further biochemical and immunological studies.

Animals↗
PubMed1993

Effects of immunization with the p12 proteins of LP-BM5 defective and ecotropic viruses on development of MAIDS.

Among murine leukemia viruses (MuLV) present in the LP-BM5 virus mixture, the agent etiologic for an acquired immunodeficiency syndrome (MAIDS) is replication defective, containing only a single open reading frame which includes all of gag. The Gag polyprotein encoded by the defective virus, termed BM5def, differs most in p12 from that of nonpathogenic ecotropic virus (BM5eco). As one approach to examining the role of p12 in disease, the ecotropic and defective virus forms of the protein, synthesized in bacteria, were used to immunize three strains of mice differing in their sensitivity to MAIDS. In each strain, both proteins elicited substantial antibody responses that were cross-reactive with either p12 and recognized the proteins as part of intact viral Gag polyproteins. Immunization with either p12 before infection with LP-BM5 viruses had no effect on the sensitivity or resistance of mice to MAIDS or on the extent of helper virus spread. The variant p12 of BM5def, when presented on its own, is thus not a crucial antigenic determinant of disease. Alternative mechanisms by which BM5def may contribute to MAIDS are discussed.

Amino Acid Sequence↗
PubMed1981

The intracellular proteins induced by cricket paralysis virus in Drosophila cells: the effect of protease inhibitors and amino acid analogues.

Treatment of Cricket paralysis virus infected Drosophila cells with iodoacetamide before radiolabelling with 35S-methionine results in the appearance of two high molecular weight polypeptides of approximately equal to 200,000 molecular weight, not apparent in untreated infected cells (17). To attempt to differentiate between the effects of iodoacetamide being attributable to either alteration of initial polyprotein or inhibition of the protease (either cellular or viral) the effects of a spectrum of protease inhibitors were examined. These included aprotinin, leupeptin, pepstatin, elevated zinc concentration, phenyl methyl sulphonyl-fluoride, N-tosyl-L-lysine chloromethyl ketone (TLCK) and N-tosyl-L-phenylalanine chloromethyl ketone (TPCK). TLCK and TPCK both inhibited the cleavage of proteins which demonstrates an inhibition of the protease activity. The introduction of amino acid analogues into the infected cells before pulsing also results in the appearance of higher molecular weight proteins. This could be attributed to alternation of the polyprotein making it nonsusceptible to digestion with pre-existing cellular protease or newly synthesized viral protease. The possibility that the presence of the amino acid analogues results in alteration of a viral coded protease cannot be eliminated.

Animals↗
PubMed1992

Processing of dengue virus type 2 structural proteins containing deletions in hydrophobic domains.

The 5' end of the genome of the dengue virus type 2 encoding the structural proteins was expressed using recombinant vaccinia virus. Three additional recombinants derived by deletion of selected dengue sequences within the parental construct were also expressed. They were designed to assess the role of hydrophobic domains in the processing of the viral polyprotein in intact cells. The first construct contained a deletion of nucleotides encoding most of the C protein; nucleotides encoding the hydrophobic domain at the carboxy terminus were retained. The second and third constructs contained smaller deletions of 72 bp and 129 bp encoding hydrophobic domains at the carboxy termini of C and prM respectively. Indirect immunofluorescence and radioimmunoprecipitation were used to detect prM and E in cells infected with recombinant viruses. The results showed that deletion of 90% of C had no apparent effect on the processing of prM and E, and that the signal sequence for E at the carboxy terminus of prM was active in the absence of the upstream signal sequence for prM at the carboxy terminus of C. Deletion of the hydrophobic sequences preceding the amino terminus of E prevented cleavage at the prM-E junction. These results obtained using infected cells were consistent with the published findings for the translation of flavivirus RNA in vitro, and indicated the importance of membrane association in the cleavage of structural proteins from the flavivirus polyprotein. In addition, cells infected with the recombinant virus containing the large deletion in the C coding region released the E glycoprotein into the culture medium.

Amino Acid Sequence↗
PubMed1993

Infectious bursal disease virus structural protein VP2 expressed by a fowlpox virus recombinant confers protection against disease in chickens.

Two fowlpox virus recombinants were constructed which expressed the host-protective antigen, VP2, of infectious bursal disease virus (IBDV). Recombinant FPV-VP 2.4.3 contained the gene for the VP 2-VP4-VP3 polyprotein under the control of the vaccinia virus late promoter P.L 11 inserted within the thymidine kinase (TK) gene of FPV. In infected chicken embryo skin (CES) cells VP2 and VP3 proteins were correctly processed from the polyprotein precursor molecule. Recombinant FPV-VP2 contained only the VP2 encoding region under the control of the fowlpox early/late promoter P.E/L inserted immediately downstream of the TK gene. The expression level of VP2 from FPV-VP2 was approximately 5 times higher than from FPV-VP2.4.3. Wing web inoculation of birds resulted in the development of typical fowlpox lesions and the development of antibodies to FPV with either of the recombinants, but only birds vaccinated with FPV-VP2 developed antibodies to IBDV. When challenged with IBDV (strain 002-73), a significant level of protection was provided by FPV-VP2 vaccination, although the level was lower than the protection provided by an oil adjuvanted inactivated whole IBDV vaccine. Birds vaccinated with FPV-VP2.4.3 were not protected from infection as assessed by ELISA for the presence of IBD virus in bursae.

Amino Acid Sequence↗
PubMed1995

Evaluation of complete genome sequences and sequences of individual gene products for the classification of hepatitis C viruses.

Comparisons of genome and polyprotein sequences of hepatitis C virus (HCV) isolates world-wide has led to the identification of nine major genotypes and many subtypes. This classification is based on either complete genome/polyprotein sequences or sequence data from the 5' noncoding region, core, E1, NS3 or NS5B genes. The relative merit of different gene segments as taxonomic markers and the validity of the resulting assignments is not clear at this stage. To resolve the taxonomy of HCV genotypes and subtypes, we have compared the complete genome and polyprotein sequences of 19 HCV isolates available in the databases as well as sequences of individual genes and gene products of these isolates. Based on the correlation between sequence relationships and taxonomic assignments of other RNA viruses, we show that the nine major genotypes of HCV represent nine distinct virus species and their subtypes subspecies. Our sequence comparison of the 5' noncoding regions and the individual gene products suggests that E2, NS2, NS5B, E1, NS4A, NS4B and NS5A (in that order) are the most appropriate regions for the discrimination between species, subspecies and strains of HCV. The 5' noncoding, core and NS3 regions are less effective in distinguishing between species, subspecies and strains. Based on a comparison of the polymerase sequence identities of HCVs, pestiviruses and flaviviruses as well as the recent information on the size and morphology of HCV virions, we propose that HCVs, pestiviruses and flaviviruses should be classified into three separate families, named Hepciviridae, Pestiviridae and Flaviviridae, respectively rather than three genera of the Flaviviridae as currently classified. We also propose "Hepcivirus" as the genus name for HCVs.

Base Sequence↗
PubMed1993

Molecular cloning and sequencing of coat protein-encoding cDNA of rice tungro spherical virus--a plant picornavirus.

Rice tungro spherical virus (RTSV) was shown to have three coat protein (CP) species by high resolution NaDodSO4-PAGE and Western blot analyses. The sequence of a coat protein-expressing cDNA clone that was identified and selected from a RTSV cDNA library showed that the insert was composed of 2823 bp with only one large open reading frame (ORF) coding for 941 amino acids. The positions of the three coat proteins were located in the putative polyprotein by N-terminal microsequencing and were shown to start at amino acids 287, 495, and 698 for CP-1, CP-2, and CP-3, respectively. The coat proteins are expressed as a polyprotein at the 5' region of the viral RNA genome, and all are cleaved at glutamine carboxy termini, presumably by picornavirus 3C-type of protease(s). Sequence comparisons of coat proteins revealed that there are high amino acid homologies between CP-2 of RTSV and VP3s of encephalomyocarditis virus (EMCV) and Theiler's murine encephalomyelitis virus (TMEV). These results indicate that RTSV is a plant picornavirus.

Amino Acid Sequence↗
PubMed1995

Complete sequence of the RNA genome of human rhinovirus 16, a clinically useful common cold virus belonging to the ICAM-1 receptor group.

We report here the complete nucleotide sequence and predicted polyprotein sequence of HeLa cell-adapted human rhinovirus 16 (HRV16). This virus is more suitable than human rhinovirus 14 (HRV14) for clinical studies, and its growth and physical properties are favorable for biochemical and crystallographic analysis. The complete message-sense RNA genome of HRV16 is composed of 7124 bases, not including the poly(A) tail. An open reading frame, extending from base 626 to 7084 predicts a polyprotein containing 2152 amino acid residues. Comparison with other rhinovirus sequences shows HRV16 is much more representative of human rhinoviruses than HRV14. No apparent relationship was found between receptor group and amino acid sequence in VP1, the capsid protein bearing the binding site for the intercellular adhesion molecule-1 (ICAM-1) in both HRV14 and HRV16.

Base Sequence↗
PubMed1992

The complete nucleotide sequence of a variant of Coxsackievirus A24, an agent causing acute hemorrhagic conjunctivitis.

The complete nucleotide sequence was determined for the cDNAs that represent the RNA genome of the standard strain of a variant of coxsackievirus A24, the EH24/70, one of the agents causing acute hemorrhagic conjunctivitis. The genome is 7461 nucleotide long and is polyadenylated at the 3'-end terminus. Following a 750-nucleotide 5'-noncoding region, there was a long open reading frame of 6642 nucleotides, which serve to encode a viral polyprotein consisting of 2214 amino acids. Comparison of the deduced amino acid sequence of the polyprotein with those of known enteroviruses allowed us to predict the possible cleavage sites. The overall structure and the organization of the RNA genome is typical for an enterovirus. Based on the similarity of the nucleotide sequence of the 5' and 3' noncoding regions, together with the amino-acid sequence of the encoded proteins, EH24/70 appeared to be closely related to polioviruses and coxsackievirus A21.

Amino Acid Sequence↗
PubMed1996

The complete nucleotide sequence and genome organization of barley mild mosaic virus (Na1 strain).

The 5'-terminal half of RNA 1 and whole of RNA 2 of barley mild mosaic bymovirus Na1 strain (BaMMV-Na1) were sequenced to give together with the published data its complete genomic sequence. BaMMV-Na1 RNA 1 and RNA 2 consist of 7263 and 3516 nucleotides, excluding the 3' poly A tails, respectively. RNA 1 encodes a single large polyprotein of 2258 amino acids (M(r) 256K), containing eight putative functional proteins, and RNA 2 also encodes one polyprotein of 891 amino acids (M(r) 98K), containing two functional proteins. These functional proteins are arranged in the same manner as in RNA 1 and RNA 2 of barley yellow mosaic bymovirus (BaYMV), and significant amino acid sequence homology (25-58%) exists between the proteins of the two viruses. The BaMMV-Na1 proteins show less amino acid sequence homology (18-32%) with the corresponding proteins of potyviruses or rymoviruses than with those of BaYMV. Comparisons of the BaMMV-Na1 proteins with the corresponding proteins of other partially sequenced BaMMV isolates show 87-98% amino acid sequence identity. There is 91-94% nucleotide sequence identity between the 3' non-coding regions (NCRs) in RNA 1 or RNA 2 of BaMMV-Na1 and other BaMMV isolates, but only 68-72% identity between the 5' NCRs in RNA 2 of BaMMV-Na1 and other BaMMV isolates.

Amino Acid Sequence↗
PubMed1995

Double-stranded RNA in rice: a novel RNA replicon in plants.

The entire sequence of 13952 nucleotides of a plasmid-like, double-stranded RNA (dsRNA) from rice was assembled from more than 50 independent cDNA clones. The 5' non-coding region of the coding (sense) strand spans over 166 nucleotides, followed by one long open reading frame (ORF) of 13716 nucleotides that encodes a large putative polyprotein of 4572 amino acid residues, and by a 70-nucleotide 3' non-coding region. This ORF is apparently the longest reported to date in the plant kingdom. Amino acid sequence comparisons revealed that the large putative polyprotein includes an RNA helicase-like domain and an RNA-dependent RNA polymerase (replicase)-like domain. Comparisons of the amino acid sequences of these two domains and of the entire genetic organization of the rice dsRNA with those found in potyviruses and the CHV1-713 dsRNA of chestnut blight fungus suggest that the rice dsRNA is located evolutionarily between potyviruses and the CHV1-713 dsRNA. This plasmid-like dsRNA in rice seems to constitute a novel RNA replicon in plants.

Amino Acid Sequence↗
PubMed1998

PsbY, a novel manganese-binding, low-molecular-mass protein associated with photosystem II.

We describe two related manganese-binding polypeptides with L-arginine metabolizing enzyme activity that can be detected as distinct components (designated PsbY-A1 and PsbY-A2, previously called L-AME) in membranes containing Photosystem II (PS II) from spinach. The polypeptides are bitopic and appear to exist in a heterodimeric form, but only in the chlorophyll a/b lineage of plants. Both proteins are encoded in the nucleus. In spinach and in Arabidopsis thaliana they are both derived from a single-copy gene (psbY) that is translated into a precursor polyprotein of approximately 20 kDa. The processing of the polyprotein is complex and includes at least four cleavage steps. Both polypeptides are exposed N-terminally to the lumenal and C-terminally to the stromal face of the thylakoid membrane.

Amino Acid Sequence↗
PubMed2003

Complete sequence of the genomic RNA of the prevalent strain of a potyvirus infecting maize in China.

The complete nucleotide sequence of the prevalent strain of a potyvirus isolated from maize in Beijing, China was determined and compared with other closely related potyviruses. The viral genome comprises 9595 nucleotides, excluding the poly (A) tail, and encodes a putative polyprotein of 3063 amino acid residues. Sequence comparison of the coat proteins showed that this isolate was most closely related to most other potyviral isolates infecting maize across China with identities of about 99% and thus represented the prevalent strain. It was also closely related to most isolates of Sugarcane mosaic virus (SCMV) infecting maize in Europe with maximum identity of about 95% at the amino acid level. The polyprotein sequence of the Beijing isolate shares identities of 98% with those of two other Chinese maize isolates and shares identity of 69% with Maize dwarf mosaic virus-Bulgarian isolate, respectively. Phylogenetic analyses of the sequences indicated that the Beijing isolate can be tentatively referred to as a prevalent strain of SCMV.

Binding Sites↗
PubMed2003

Sequence analysis demonstrates that Onion yellow dwarf virus isolates from China contain a P3 region much larger than other potyviruses.

The complete sequence of an isolate of Onion yellow dwarf virus (OYDV) from Yuhang, Zhejiang province, China, was determined. It was 10538 nts in length and was predicted to encode a polyprotein 3403 amino acids (aa) long with a calculated M(r) of 385.1 kDa. The predicted P3 protein (530 aa) was larger than that of any of the potyviruses sequenced to date (344-378 aa). The additional sequence occurs at the N-terminus of the protein, does not represent a duplication from elsewhere in the OYDV genome and could not be matched to any other sequences in the databases. Similar sequences were found in 4 other Chinese OYDV isolates. Phylogenetic analysis of the amino acid sequences of the polyprotein showed that OYDV is distantly related to Pea seed-borne mosaic virus and the potyviruses of grasses and cereals.

Amino Acid Sequence↗
PubMed2003

The complete nucleotide sequence of Plum pox virus isolates from sweet (PPV-SwC) and sour (PPV-SoC) cherry and their taxonomic relationships within the species.

Plum pox virus (PPV) sweet (SwC) and sour (SoC) cherry isolates were the first PPV isolates to be recovered from natural infection in sweet and sour cherry plants, respectively. Their complete nucleotide sequences have been determined finding a deduced genome organisation typical for PPV species. Both genomes are 9795 nucleotides long, excluding the 3' terminal poly(A) tail, and contain an open reading frame of 9432 nt, encoding a polyprotein of 3143 amino acids. The nucleotide and predicted amino acid sequences of PPV-SwC and SoC have been pairwise compared with available sequences of different PPV strains. Although a very high similarity exists between the whole genomes and polyproteins of the two cherry isolates, high levels of divergence have been calculated with sequences of PPV-M, D and EA isolates. In particular, the most considerable divergence has been found in part of 5' non coding region, in regions encoding P1, P3 + 6K1, 6K2 and NIa-VPg proteins as well as in the N-terminal domain of the coat protein. Phylogenetic analysis have been undertaken in order to establish the taxonomic localisation of SwC and SoC isolates within PPV species, showing that they are always clustered together and separated from the rest of PPV strains, being clearly the most distant.

5' Untranslated Regions↗