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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Nucleotide sequencing of a virulent African swine fever virus (ASFV) isolate (Malawi LIL20/1) identified an open reading frame of 1191 amino acid residues encoding a protein of 134.9 kDa. This gene mapped to the SalI i and j restriction endonuclease fragments of the ASFV genome. The predicted polypeptide was found to share 21.1% identity over a 1077 amino acid region with the human type II DNA topoisomerase. The sequence is compared to other type II DNA topoisomerases and the possible roles in ASFV replication are discussed.
J Mol Biol 1992 Dec 05
PMID:African swine fever virus encodes a gene with extensive homology to type II DNA topoisomerases. 133 84

Adenovirus E1A pre-mRNA was used as a model to examine alternative 5' splice site selection during in vitro splicing reactions. Strong preference for the downstream 13S 5' splice site over the upstream 12S or 9S 5' splice sites was observed. However, the 12S 5' splice site was used efficiently when a mutant pre-mRNA lacking the 13S 5' splice site was processed, and 12S splicing from this substrate was not reduced by 13S splicing from a separate pre-mRNA, demonstrating that 13S splicing reduced 12S 5' splice site selection through a bona fide cis-competition. DEAE-cellulose chromatography of nuclear extract yielded two fractions with different splicing activities. The bound fraction contained all components required for efficient splicing of simple substrates but was unable to utilize alternative 5' splice sites. In contrast, the flow-through fraction, which by itself was inactive, contained an activity required for alternative splicing and was shown to stimulate 12S and 9S splicing, while reducing 13S splicing, when added to reactions carried out by the bound fraction. Furthermore, the activity, which we have called distal splicing factor (DSF), enhanced utilization of an upstream 5' splice site on a simian virus 40 early pre-mRNA, suggesting that the factor acts in a position-dependent, substrate-independent fashion. Several lines of evidence are presented suggesting that DSF is a non-small nuclear ribonucleoprotein protein. Finally, we describe a functional interaction between DSF and ASF, a protein that enhances use of downstream 5' splice sites.
Mol Cell Biol 1991 Dec
PMID:A novel protein factor is required for use of distal alternative 5' splice sites in vitro. 165 20

Nucleotide sequencing identified a tandemly repeated sequence array 22 x 10(3) base-pairs from the right-hand DNA terminus of the African swine fever virus (ASFV) genome. The sequence of the repeat array and sequences closely flanking it were compared in the genomes of four groups of ASFV isolates that had very different restriction enzyme site maps. Arrays present in one group of ASFV isolates from East Zambia/Malawi varied in length and contained between 8 and 38 copies of a 17-nucleotide repeat unit. Repeat arrays in a second group of ASFV isolates from Europe were less variable in length but consisted of different types of repeat unit that were divergent in sequence. A third genetically diverse ASFV isolate. LIV 13 from a South Zambia Game Park, contained repeat unit types that were similar to those of European viruses. MFUE6 isolate from an East Zambia Game Park contained a shorter version of the European repeat unit. An eight-base-pair core sequence was conserved between the East Zambia/Malawi and European and LIV 13 repeat units. These tandemly repeated sequence arrays share a number of properties with chromosomal minisatellite DNA. Similar tandem repeat arrays have not been described in poxviruses.
J Mol Biol 1990 Dec 05
PMID:Identification of a variable region of the African swine fever virus genome that has undergone separate DNA rearrangements leading to expansion of minisatellite-like sequences. 225 35

African swine fever virus polypeptides with molecular weight of 120, 78, 69, 59, 56, 45, 39, 28, 26, 24, 16, and 14 kD are the major proteins in the purified virions, as shown by electrophoresis and immunoblotting. A mixture of proteases and pancreatic lipase hydrolyzed the polypeptides of 120 and 78 kD in viral preparations at low concentrations of enzymes, polypeptides of 69, 56, 45, 39, 28, and 14 kD disappeared after treatment with this mixture at medium concentrations, and 26 kD polypeptide was eliminated at a high concentration of the enzymes. The 21 kD polypeptide which did not react with the specific antiviral serum in immunoblotting was not hydrolyzed by proteases contaminating lipase. Treatment with triton X-100 and ether boosted the activity of DNA-dependent RNA-polymerase, whereas treatment with ether followed by resedimentation markedly decreased polymerase activity in the resultant sediment. Treatment with diethyl ether did not influence the activity of virus-associated ATPase, which was partially resistant to denaturating organic solvents acetone and chloroform-methanol mixture. Our findings and published data permitted us to propose a schematic arrangement of viral polypeptides and enzymes in the virion structure.
Mol Gen Mikrobiol Virusol
PMID:[Localizing the major peptides of African swine fever virus and virus-associated enzymes in the virion structure]. 747 38

Routine electronmicroscopic examination of interactions between African swine fever virus and mononuclear phagocytes showed signs of apoptosis as a morphological phenomenon and form of cellular death in an infected culture treated with defective interfering virus particles and in target cells under the effect of virus specific cytotoxic T-lymphocytes. The morphology of induced apoptosis in the aforesaid virus-cell system is illustrated and described in detail.
Mol Gen Mikrobiol Virusol
PMID:[Apoptosis in the African swine fever virus-swine mononuclear phagocyte system]. 747 39

The essential splicing factor SF2/ASF and the heterogeneous nuclear ribonucleoprotein A1 (hnRNP A1) modulate alternative splicing in vitro of pre-mRNAs that contain 5' splice sites of comparable strengths competing for a common 3' splice site. Using natural and model pre-mRNAs, we have examined whether the ratio of SF2/ASF to hnRNP A1 also regulates other modes of alternative splicing in vitro. We found that an excess of SF2/ASF effectively prevents inappropriate exon skipping and also influences the selection of mutually exclusive tissue-specific exons in natural beta-tropomyosin pre-mRNA. In contrast, an excess of hnRNP A1 does not cause inappropriate exon skipping in natural constitutively or alternatively spliced pre-mRNAs. Although hnRNP A1 can promote alternative exon skipping, this effect is not universal and is dependent, e.g., on the size of the internal alternative exon and on the strength of the polypyrimidine tract in the preceding intron. With appropriate alternative exons, an excess of SF2/ASF promotes exon inclusion, whereas an excess of hnRNP A1 causes exon skipping. We propose that in some cases the ratio of SF2/ASF to hnRNP A1 may play a role in regulating alternative splicing by exon inclusion or skipping through the antagonistic effects of these proteins on alternative splice site selection.
Mol Cell Biol 1993 May
PMID:Modulation of exon skipping and inclusion by heterogeneous nuclear ribonucleoprotein A1 and pre-mRNA splicing factor SF2/ASF. 847 57

The nature of the bcl-2 family of proto-oncogenes was analyzed by sequence alignment, secondary structure prediction, and phylogenetic techniques. Phylogenies were inferred from both the nucleic acid and amino acid sequences of the human, murine, rat, and chicken sequences for BCL-2 and BCL-X, human MCL1, murine A1, the nematode Caenorhabditis elegans and Caenorhabditis briggsiae ced-9 proteins, and the sequences BHRF1 from Epstein-Barr and LMW5-HL from African swine fever viruses. Both sequence alignment and secondary structure prediction techniques supported the conservation of both the overall secondary structure and the carboxy-terminal transmembrane domain in all members of the family. All the treeing methods employed (distance matrix, maximum likelihood, and parsimony) supported a tree in which the proapoptotic proteins BCL-2 and BCL-X represent the most recent additions to the group. All the trees also indicated that the viral proteins BHRF1 and LMW-HL arose from a common ancestor, an ancestor they shared in common with the pro-apoptotic control protein BAX, indicating that this function of BAX evolved only recently. The most ancient branches are represented by the nematode ced-9 protein and by the control genes MCL1 and A1, which in the treeing methods employed represent separate lineages within the most ancient grouping. These results demonstrate the evolution of a highly conserved family of developmental control genes from nematode to man--genes that encode proteins essential for normal development but which are highly conserved in terms of predicted structure and possible cellular localization. The evolutionary analysis also indicates that the family may be even larger than originally predicted and that other members are waiting to be discovered.
J Mol Evol 1995 Dec
PMID:Molecular evolution and secondary structural conservation in the B-cell lymphoma leukemia 2 (bcl-2) family of proto-oncogene products. 858 22

Fusion of African swine fever virus (ASFV) with model membranes was monitored by a fluorescence dequenching assay. ASFV was able to fuse with liposomes of various compositions. Fusion was more extensive with liposomes made of negatively charged phospholipids, and reduced in the presence of the neutral phospholipid phosphatidylcholine (PC). Fusion activity of ASFV was pH-dependent, the extent of fusion increasing with decreasing pH for all target membranes. These results are consistent with the in vivo characteristics of fusion of ASFV with the endosome membrane. An increase in fusion activity was obtained with dehydrating agents, similarly to what occurs with other lipid-enveloped viruses. Dehydrating agents such as dimethylsulfoxide and dimethylsulfone greatly enhanced fusion, the effect of dimethylsulfone being more pronounced than that of dimethylsulfoxide. Poly(ethylene glycol) also potentiated ASFV fusion activity, and the effect of this polymer was found to be dependent on its molecular weight. These results stress the importance of dehydration and hydrophobic interactions on the early events of viral penetration into target cells.
Biochem Mol Biol Int 1995 Oct
PMID:Fusion activity of African swine fever virus towards target membranes: lipid dependence and effect of dehydrating agents. 859 88

The accumulation in infected cells of large amounts of unspliced viral RNA for use as mRNA and genomic RNA is a hallmark of retrovirus replication. The negative regulator of splicing (NRS) is a long cis-acting RNA element in Rous sarcoma virus that contributes to unspliced RNA accumulation through splicing inhibition. One of two critical sequences located in the NRS 3' region resembles a minor class 5' splice site and is required for U11 small nuclear ribonucleoprotein (snRNP) binding to the NRS. The second is a purine-rich region in the 5' half that interacts with the splicing factor SF2/ASF. In this study we investigated the possibility that this purine-rich region provides an RNA splicing enhancer function required for splicing inhibition. In vitro, the NRS acted as a potent, orientation-dependent enhancer of Drosophila doublesex pre-mRNA splicing, and enhancer activity mapped to the purine-rich domain. Analysis of a number of site-directed and deletion mutants indicated that enhancer activity was diffusely located throughout a 60-nucleotide area but only the activity associated with a short region previously shown to bind SF2/ASF correlated with efficient splicing inhibition. The significance of the enhancer activity to splicing inhibition was demonstrated by using chimeras in which two authentic enhancers (ASLV and FP) were substituted for the native NRS purine region. In each case, splicing inhibition in transfected cells was restored to levels approaching that observed for the NRS. The observation that a nonfunctional version of the FP enhancer (FPD) that does not bind SF2/ASF also fails to block splicing when paired with the NRS 3' region supports the notion that SF2/ASF binding to the NRS is relevant, but other SR proteins may substitute if an appropriate binding site is supplied. Our results are consistent with a role for the purine region in facilitated snRNP binding to the NRS via SF2/ASF.
Mol Cell Biol 1998 Jun
PMID:An RNA splicing enhancer-like sequence is a component of a splicing inhibitor element from Rous sarcoma virus. 958 51

We have identified multiple distinct splicing enhancer elements within protein-coding sequences of the constitutively spliced human beta-globin pre-mRNA. Each of these highly conserved sequences is sufficient to activate the splicing of a heterologous enhancer-dependent pre-mRNA. One of these enhancers is activated by and binds to the SR protein SC35, whereas at least two others are activated by the SR protein SF2/ASF. A single base mutation within another enhancer element inactivates the enhancer but does not change the encoded amino acid. Thus, overlapping protein coding and RNA recognition elements may be coselected during evolution. These studies provide the first direct evidence that SR protein-specific splicing enhancers are located within the coding regions of constitutively spliced pre-mRNAs. We propose that these enhancers function as multisite splicing enhancers to specify 3' splice-site selection.
Mol Cell Biol 1999 Jan
PMID:Multiple distinct splicing enhancers in the protein-coding sequences of a constitutively spliced pre-mRNA. 985 50


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