Publications
| Title | Abstract | Year Filter | PMID(sorted descending) Filter |
|---|
| binding of the e1 and e2 proteins to the origin of replication of bovine papillomavirus. | dna replication of bovine papillomavirus (bpv) requires two viral proteins encoded from the e1 and e2 open reading frames. e1 and e2 are sequence-specific dna binding proteins that bind to their cognate binding sites in the bpv origin of replication (ori). the e1 and e2 proteins can interact physically with each other, and this interaction results in cooperative binding when binding sites for both proteins are present. we have analyzed the binding of e1 to the ori in the absence and presence of ... | 1997 | 9060646 |
| identification of papillomaviruses in scrapings from bovine warts by use of the polymerase chain reaction. | 1997 | 9060144 | |
| a mutation study of the dna binding domain of human papillomavirus type11 e2 protein. | a site-specific mutation study was performed on the c-terminal domain, containing a cloned dna binding region, of the human papillomavirus type11 (hpv11) e2 protein to determine the specific properties of residues directly involved in the dna binding. the effect of a point mutations on the dna binding was assessed by means of a gel mobility shift assay. the mutagenesis was concentrated on the residues in the third helix from the n-terminal, that is known as the "recognition helix," in the crysta ... | 1997 | 9058204 |
| cell lines containing and expressing the human herpesvirus 6a ts gene are protected from both h-ras and bpv-1 transformation. | human herpesvirus 6a (hhv-6a) strain u1102 was previously shown to contain a 1473 bp transformation suppressor gene (ts) (araujo et al., 1995). ts inhibited transformation of nih3t3 cells by h-ras and transcription of the h-ras and human immunodeficiency type 1 (hiv-1) promoters in transient transfection experiments. in the current study, stable nih3t3 cell lines expressing ts protein were established by transfection with prc-ts containing the ts gene under the control of the rous sarcoma virus ... | 1997 | 9050993 |
| mutations in the human papillomavirus type 16 e2 protein identify a region of the protein involved in binding to e1 protein. | papillomavirus dna replication is primarily dependent upon two viral gene products, e1 and e2. work with bovine papillomavirus has shown that the e2 protein can bind directly to the e1 protein and enhance the binding of e1 to the viral origin of replication. however, little is known about the mechanism of interaction between e1 and e2 proteins. in this study we have analysed in detail the association between human papillomavirus type 16 (hpv-16) e1 and e2 proteins. using a purified glutathione s ... | 1995 | 9049327 |
| multiplicity of uses of monoclonal antibodies that define papillomavirus linear immunodominant epitopes. | during the last 10 yr, we have derived monoclonal antibodies from animals immunized with denatured bovine papillomaviruses type 1 major capsid (l1) protein, mapped their corresponding immunodominant epitopes to within a single amino acid (aa), and compared the reactivity of authentic l1 proteins to the predicted response by collinear analysis of the aa sequences of the same and other papillomaviruses (pvs). the data obtained from this approach has provided us with new insights into the sensitivi ... | 1997 | 9048212 |
| expression of the papillomavirus e2 protein in hela cells leads to apoptosis. | the papillomavirus e2 protein plays a central role in the viral life cycle as it regulates both transcription and replication of the viral genome. in this study, we showed that transient expression of bovine papillomavirus type 1 or human papillomavirus type 18 (hpv18) e2 proteins in hela cells activated the transcriptional activity of p53 through at least two pathways. the first one involved the binding of e2 to its recognition elements located in the integrated viral p105 promoter. e2 binding ... | 1997 | 9034333 |
| modulation of bovine papillomavirus dna replication by phosphorylation of the viral e1 protein. | e1 is the dna replication origin recognition protein for bovine papillomavirus (bpv), and it carries out enzymatic functions required for initiation of viral dna replication. cellular mechanisms likely play a role in regulating bpv dna replication. we are investigating the role of phosphorylation of e1 on viral replication in vivo and on e1 activity in vitro. serine 109 is a phosphoacceptor in vivo and is targeted by protein kinase a and protein kinase c in vitro. a viral genome carrying a serin ... | 1997 | 9024804 |
| age distribution of antibodies to human papillomavirus in children, women with cervical intraepithelial neoplasia and blood donors from south africa. | sera from 95 women with cervical intraepithelial neoplasia (cin), 95 age-matched female blood donors, and 155 children aged between 1 and 12 years were tested by enzyme-linked immunosorbent assay (elisa) for levels of serum igg to three human papillomavirus (hpv) peptides (hpv-16 e2 [e2-16], hpv-18 e2 (e2-18], hpv-16 l1 [l1-16]), as well as hpv-16 virus-like particles (vlp-16) and bovine papillomavirus type 1 virus-like particles (bpv-vlp). in the adult group antibodies to e2-16 and vlp-16 were ... | 1997 | 9021543 |
| sequence close to the n-terminus of l2 protein is displayed on the surface of bovine papillomavirus type 1 virions. | the bovine papillomavirus type 1 (bpv1) l2 protein purified from escherichia coli was used as an antigen to produce monoclonal antibodies (mabs). a total of 26 individual clones which recognized the bpv1 l2 protein were obtained. using infectious bpv1 virus particles, 3 of the mabs were found to interact with bpv1 virus particles. binding of the mabs to bpv1 was confirmed by immunoelectron microscopy. a set of 92 13-mer peptides overlapping by 8 amino acids spanning the entire bpv1 l2 protein wa ... | 1997 | 9018146 |
| casein kinase ii phosphorylates bovine papillomavirus type 1 e1 in vitro at a conserved motif. | the e1 protein of bovine papillomavirus type 1 (bpv-1) is a phosphoprotein which specifically binds and unwinds the virus replication origin by atp-dependent helicase activity. the el protein has been shown to be multiply phosphorylated in vivo, although the sites of modification are incompletely mapped. examination of the predicted amino acid sequence of all available e1 proteins revealed strong conservation between amino acids 25 and 60 of a motif consisting of a serine residue followed by a s ... | 1997 | 9010301 |
| visualization of multicomponent transcription factor complexes on chromatin and nonnucleosomal templates in vivo. | there is increasing evidence that specific chromatin structures play an important role in the regulation of transcription in eukaryotes. the mouse mammary tumor virus (mmtv) promoter, which is reproducibly assembled into a phased array of six nucleosomes when introduced into cells, represents a particularly well-studied example. the second or b nucleosome of the phased array is disrupted in response to hormone stimulation, allowing the assembly of a preinitiation complex and the activation of tr ... | 1997 | 8993036 |
| isolation of an amino-terminal region of bovine papillomavirus type 1 e1 protein that retains origin binding and e2 interaction capacity. | in vitro dna binding results from a series of e1 proteins containing amino-terminal or carboxy-terminal truncations indicated that sequences between amino acids 121 and 284 were critical for origin binding. additional binding experiments with e1 proteins containing internal, in-frame insertions or deletions confirmed the importance of the region defined by truncated e1 proteins and also demonstrated that downstream sequences were not required for binding activity in the context of the full-lengt ... | 1997 | 8985429 |
| sequences flanking the core dna-binding domain of bovine papillomavirus type 1 e2 contribute to dna-binding function. | we have compared a series of molecular constructs that contain the minimal dna-binding and dimerization domain of bovine papillomavirus type 1 (bpv-1) e2 alone or this binding domain plus the adjacent 16 or 40 amino acids to test the role of the flanking sequences in e2 function. the presence of these sequences resulted in an up to eightfold increase in the affinity of e2 for its target dna and stabilized the protein against denaturation both in the absence of dna and in the form of dna-protein ... | 1997 | 8985425 |
| altered susceptibility to tumor necrosis factor alpha-induced apoptosis of mouse cells expressing polyomavirus middle and small t antigens. | infection with some virus types induces susceptibility to the cytotoxic effect of tumor necrosis factor alpha (tnf-alpha). to investigate whether expression of polyomavirus proteins has this effect on cells, the tnf-alpha sensitivity of c127 and l929 mouse cells transfected with viral dna was analyzed. expression of all three polyomavirus early proteins, the tumor (t) antigens, had no apparent effect. in contrast, middle t antigen by itself induced hypersensitivity to tnf-alpha. this effect was ... | 1997 | 8985347 |
| dose-dependent regulation of the early promoter of human papillomavirus type 18 by the viral e2 protein. | the activity of the e6/e7 promoter of genital human papillomaviruses (hpvs) is positively and negatively modulated by a complex interplay between a variety of cellular transcription factors and the virally encoded e2 protein. the long control region of genital hpvs contains four e2 binding sites in conserved positions, two of which are very close to the tata box. binding of e2 to these two sites has been shown to repress the promoter. to carefully analyze the effect of e2 on the activity of the ... | 1997 | 8985322 |
| the bovine papillomavirus type 4 e8 protein binds to ductin and causes loss of gap junctional intercellular communication in primary fibroblasts. | the e8 open reading frame of bovine papillomavirus type 4 encodes a small hydrophobic polypeptide which contributes to cell transformation by conferring anchorage-independent growth. using an in vitro translation system, we show that the e8 polypeptide binds to ductin, the 16-kda proteolipid that forms transmembrane channels in both gap junctions and vacuolar h+-atpase. this association is not due to nonspecific hydrophobic interactions. ppa1, a saccharomyces cerevisiae polypeptide homologous (w ... | 1996 | 8971040 |
| phenotypical characterization of lymphocytes infiltrating regressing papillomas. | papillomavirus-induced lesions often regress spontaneously in both humans and animals. papilloma regression is deemed to be due to a cell-mediated immune response, the nature of which is still ill defined, and is accompanied by immune cell infiltrates. to gain further information on the nature and role of the immune cells present in regressing papillomas, we have analyzed biopsies of papillomas induced in the soft palate of cattle by bovine papillomavirus type 4 (bpv-4) and have phenotypically c ... | 1996 | 8970967 |
| conditional requirement for sequences distinct from the replication origin during episomal establishment of the bpv1 genome. | removal from bpv1 dna of a short segment (nt. 4786-5045) that contains several protein binding sites and is required for efficient replication in short term assays prevents its autonomous maintenance in cell lines established by selection in g418 medium after cotransfer of neo(r). in contrast, transformed cell lines established from foci, which express the viral genes at higher levels, maintain extrachromosomal copies of the deleted dna. two modes of maintenance of the viral genome are thus dist ... | 1996 | 8954917 |
| bovine papillomavirus oncoprotein e5 induces the nf kappa b activation through superoxide radicals. | bovine papillomavirus type 1 (bpv-1) open reading frame e5 encodes the smallest known oncoprotein. this protein is involved in transforming cells during the early stage of infection. nuclear factor kappa b (nf kappa b) is activated in the host cells as a result of different virus infections. it has been shown that reactive oxygen intermediates activate nf kappa b which leads the activation of several cellular genes. we studied the effect of bpv-1 es protein on nf kappa b activation. we found tha ... | 1996 | 8950027 |
| the e5 gene product of rhesus papillomavirus is an activator of endogenous ras and phosphatidylinositol-3'-kinase in nih 3t3 cells. | we examined the effect of two rhesus papillomavirus 1 (rhpv) oncogenes on cytokine-induced signal transduction pathways leading to the possible activation of ras protein (p21ras) and phosphatidylinositol kinase. p21ras in both the activated (gtp-bound) and inactivated (gdp-bound) states were quantitated. nih 3t3 cell lines expressing the rhpv 1 e5 gene or epidermal growth factor receptor cdna had about a sixfold higher ratio of p21ras-bound gtp to p21ras-bound gdp as compared with parental nih 3 ... | 1996 | 8917513 |
| e2 proteins: modulators of papillomavirus transcription and replication. | 1996 | 8902804 | |
| enhanced transcriptional activation by e2 proteins from the oncogenic human papillomaviruses. | a systematic comparison of transcriptional activation by papillomavirus e2 proteins revealed that the e2 proteins from high-risk human papillomaviruses (human papillomavirus type 16 [hpv-16] and hpv-18) are much more active than are the e2 proteins from low-risk hpvs (hpv-6b and hpv-11). despite the tropism of hpvs for particular epithelial cell types, this difference in transcriptional activation was observed in a number of different epithelial and nonepithelial cells. the enhanced activities o ... | 1996 | 8892874 |
| the initiator protein e1 binds to the bovine papillomavirus origin of replication as a trimeric ring-like structure. | the replication initiator protein e1 binds to the origin of replication of bovine papillomavirus in several forms. e1 can bind to its recognition sequence as a monomer together with the viral transcription factor e2, or as a trimeric e1 complex. the trimerization of e1 is mediated by the sequence-specific binding of e1 to dna, and results in an e1 complex that is linked topologically to the dna because the three molecules of e1 form a ring-like structure that encircles the dna. these results dem ... | 1996 | 8890182 |
| tumour suppressor gene p53 in the horse: identification, cloning, sequencing and a possible role in the pathogenesis of equine sarcoid. | the tumour suppressor protein p53 enhances the genetic stability of the cell and plays a critical role in tumour suppression. equine p53 was analysed by sequencing exons 5 to 9, a region which includes most known mutations and all the mutational hotspots in the species that have been investigated. the fragment was amplified, cloned and sequenced from genomic and complementary dna. a comparison of the predicted amino acid sequences between the horse and other species resulted in identities betwee ... | 1996 | 8880979 |
| ebna1 and e2: a new paradigm for origin-binding proteins? | 1996 | 8868083 | |
| status and transcriptional activity of a bovine-papillomavirus-i-based expression vector in a recombinant production cell line. | we have analysed the status and transcriptional activity of the bovine papillomavirus-i (complete bpv-i genome)-based expression vector pces in ci27i-cell-line-derived 3ti cells used for the industrial production of recombinant human erythropoietin (rhuepo). complete tandem head-to-tail integration of about 600 vector copies at a single site of the cellular genome was observed. deletions, insertions or rearrangements of pces-specific sequences or extrachromosomal copies of vector sequences were ... | 1996 | 8867900 |
| different arrangement of human papillomavirus e2 binding sites distinguishes cutaneous types from those associated with mucosal lesions. | high-risk-type human papillomavirus dna sequences are found in a high percentage of carcinomas from the uterine-cervix, with the viral e1-e2 gene region usually disrupted and the e6 and e7 oncoproteins consistently expressed. the e2 protein is known to repress early transcription from genital hpv promoters having a proximal e2 binding site (e2bs) close to the tata box. on the contrary, the e2 protein activates cutaneous early promoters having a longer distance between these sites. using an in vi ... | 1996 | 8854400 |
| the atp-binding and atpase activities of human papillomavirus type 16 e1 are significantly weakened by the absence of prolines in its atp-binding domain. | the e1 protein of human papillomavirus (hpv) type 16 is the only known papillomavirus e1 which does not contain any proline residues in the phosphate-loop (p-loop) of its atp-binding site. to ascertain whether this feature influences the activities of hpv-16 e1, we generated a mutant hpv-16 e1 (e1pro) in which prolines are inserted in place of alanines in this site, making the p-loop identical to its bovine papillomavirus type 1 counterpart. glutathione s-transferase (gst) fusion proteins (gste1 ... | 1995 | 8847499 |
| serologic association between human papillomavirus type 16 infection and esophageal cancer in shaanxi province, china. | the existence of large geographic variations in the prevalence of esophageal cancer in some countries, such as china, indicates that environmental risk factors may be important in the development of this disease. some studies have implicated genital-mucosal strains of human papillomaviruses (hpvs) in the etiology of this cancer. | 1996 | 8841021 |
| carboxyl terminus of bovine papillomavirus type-1 l1 protein is not required for capsid formation. | the papillomavirus major capsid protein l1 can assemble into capsids in vitro. to identify areas within the bovine papillomavirus type-1 l1 (bpv l1) protein that are important for virus assembly, we constructed a set of 24 baculovirus recombinants expressing bpv l1 deletion mutants that span the entire l1 open reading frame. virus-like particle (vlp) formation of the l1 mutants was examined by electron microscopy. wild-type (wt) bpv l1 expressed in recombinant baculovirus formed vlps, while caps ... | 1996 | 8806558 |
| surface conformational and linear epitopes on hpv-16 and hpv-18 l1 virus-like particles as defined by monoclonal antibodies. | a panel of 24 monoclonal antibodies (mabs) was generated against human papillomavirus (hpv) types 16 and 18 l1 virus-like particles (vlps). the mabs were screened for reactivity to a variety of vlps prepared from hpv-6, -11, -16, -18, -31, -33, -35, and -45, cottontail rabbit papillomavirus, bovine papillomavirus type 1, and a set of 35 overlapping 20-amino-acid peptides spanning the entire hpv-16 l1 gene. type-specific linear and conformational surface epitopes were detected as well as several ... | 1996 | 8806551 |
| transcriptional activation function is not required for stimulation of dna replication by bovine papillomavirus type 1 e2. | bovine papillomavirus type 1 replication was previously shown to require both the e1 initiator protein and the e2 transactivator protein. we show here that e1, in the absence of e2, is sufficient for low-level bovine papillomavirus type 1 dna replication in c-33a cells. in addition, studies of genetically isolated e2 point mutants demonstrate that enhancement of replication by e2 does not require its transcriptional activation function. the uncoupling of the e2 functions suggests that stimulatio ... | 1996 | 8794380 |
| characterization of the single-strand-specific bpv-1 origin binding protein, spsf i, as the hela pur alpha factor. | spsf i and ii are two cellular proteins which bind specifically to single-stranded dna. spsf i and ii binding sites are found in the minimal origin of replication of bpv-1 dna and near the p2 promoter of the cellular c-myc gene. dna-binding properties of the two proteins to single-stranded oligonucleotides of different lengths and sequences were quantified by determination of dna-binding constants. the binding constant of spsf proteins to the lower strand of the bpv-1 origin was determined to be ... | 1996 | 8759014 |
| vaccination of cattle with bovine papillomavirus type 4 l2 elicits the production of virus-neutralizing antibodies. | prophylactic vaccination of cattle with the n terminus (l2a, aa 11-200) of the minor capsid protein l2 completely prevented bovine papillomavirus type 4 (bpv-4) infection of the alimentary canal. to investigate the mechanisms underlying protection from viral infection, sera from vaccinated animals were analysed in neutralization assays both in the nude mouse xenograft system and in cattle. bpv-4 retained its infectivity when incubated with preimmune cattle sera, whereas, when incubated with immu ... | 1996 | 8758002 |
| bovine papillomavirus type 4 dna isolated from a skin lesion in a steer. | a lesion on the head of a steer, defined histologically as an epithelial papilloma, yielded dna which did not hybridise with any of the bovine papillomavirus dnas usually associated with the formation of skin lesions. dna from the lesion did hybridise with dna from bovine papillomavirus 4, even under stringent conditions, and contained a sequence that could be amplified by polymerase chain reaction with primers specific for that virus. bovine papillomavirus 4 had previously been isolated only fr ... | 1996 | 8733180 |
| transcriptional and replicational activation functions in the bovine papillomavirus type 1 e2 protein are encoded by different structural determinants. | a set of e2 proteins with mutations in the amino-terminal transactivation domain was made by a scheme called clustered charged-to-alanine scan. these mutant e2 proteins were tested for expression, stability, and compartmentalization in cells and for sequence-specific dna binding, as well as in functional assays for transcriptional and replicational activation. we identified four groups of mutants. first, mutants k111a, k112a, and e176a were unable to activate replication and transcription becaus ... | 1996 | 8709243 |
| in vitro generation and type-specific neutralization of a human papillomavirus type 16 virion pseudotype. | we report a system for generating infectious papillomaviruses in vitro that facilitates the analysis of papillomavirus assembly, infectivity, and serologic relatedness. cultured hamster bphe-1 cells harboring autonomously replicating bovine papillomavirus type 1 (bpv1) genomes were infected with recombinant semliki forest viruses that express the structural proteins of bpv1. when plated on c127 cells, extracts from cells expressing l1 and l2 together induced numerous transformed foci that could ... | 1996 | 8709207 |
| transgenic models for papillomavirus-associated multistep carcinogenesis. | to investigate the physiological and pathological in vivo functions of molecularly cloned genes, the transgenic mouse is one of the most useful experimental animal systems. many kinds of transgenic mice carrying papillomavirus genes have been produced, and the studies have revealed several new aspects in the field of papillomaviral oncology. among these transgenic mice, the mechanism of skin carcinogenis in the bovine papillomavirus (bpv) transgenic mouse has been well characterized, demonstrati ... | 1995 | 8682614 |
| simple procedure for creation of in-frame deletion mutations throughout an open reading frame. | a general method is presented for randomly mutagenizing open reading frames (orf) to generate in-frame deletions and insertions. the protocol requires expression of the orf of interest as a hybrid orf-beta-galactosidase fusion protein. this allows colorimetric screening for beta-galactosidase activity during subsequent mutagenesis steps. consequently, proteins with no suitable phenotypic selection or screening properties can be readily screened for mutations that disrupt and subsequently restore ... | 1996 | 8679203 |
| selection of the bovine papillomavirus type 1 nucleotide 3225 3' splice site is regulated through an exonic splicing enhancer and its juxtaposed exonic splicing suppressor. | alternative splicing is an important mechanism for the regulation of bovine papillomavirus type 1 (bpv-1) gene expression during the virus life cycle. however, one 3' splice site, located at nucleotide (nt) 3225, is used for the processing of most bpv-1 pre-mrnas in bpv-1-transformed c127 cells and at early to intermediate times in productively infected warts. at late stages of the viral life cycle, an alternative 3' splice site at nt 3605 is used for the processing of the late pre-mrna. in this ... | 1996 | 8676495 |
| genetic analysis of the activation domain of bovine papillomavirus protein e2: its role in transcription and replication. | the bovine papillomavirus protein e2 serves dual functions in viral transcription and in the initiation of viral replication. as a transcription factor, e2 can cooperatively interact with cellular proteins such as sp1 and stimulate transcription of distal promoters. in replication, e2 and the helicase el are the only viral proteins required for accurate replication of templates containing the viral origin. the amino terminus of e2 is a functionally separable domain critical for activation of bot ... | 1996 | 8676438 |
| [specific serologic studies with a novel authentic hpv antigen (virus-like particles) for hpv-6 antibodies in gynecologic patient samples]. | a serological assay for genital hpv infection would provide important additional information to hpv dna diagnostic methods, since it would evaluate prior exposure to the viruses, detect significant systemic immunologic response to virus infection, and could be performed in most clinical laboratories. | 1995 | 8672922 |
| swelling and ca2+-activated anion conductances in c127 epithelial cells expressing wt and delta f508-cftr. | cftr is a chloride channel that is required for fluid secretion and salt absorption in many exocrine epithelia. mutations in cftr cause cystic fibrosis. cftr expression influences some ion channels, but the range of channels influenced, the mechanism of the interaction and the significance for cystic fibrosis are not known. possible interactions between cftr and other ion channels were studied in c127 mouse mammary epithelial cell lines stably transfected with cftr, delta f508-cftr, or vector. c ... | 1996 | 8661514 |
| the transactivation and dna binding domains of the bpv-1 e2 protein have different roles in cooperative origin binding with the e1 protein. | the bovine papillomavirus e2 transactivator protein enhances the ability of the e1 protein to bind to the viral origin of replication which contains an e1 binding site flanked by two e2 binding sites. to determine which regions and functions of the e2 protein are important for this cooperative interaction, a series of mutated e2 proteins were assayed for their ability to enhance e1 origin-specific binding. cooperative origin binding required at least one e2 dna binding site, an intact functional ... | 1996 | 8661413 |
| genetic analysis of the bovine papillomavirus e2 transcriptional activation domain. | the bovine papillomavirus type 1 e2 transactivator has a large amino-terminal 215-residue transcriptional activation domain (tad) that is active in saccharomyces cerevisiae and higher eukaryotic cells. comparison to other transcriptional activators suggests that its functions may be mediated in part through two acidic regions, a1 and a2, in this domain. we have characterized the functional elements within the e2 tad using lexa-e2 fusions and by screening randomly generated libraries of e2 mutati ... | 1996 | 8661412 |
| conserved features in papillomavirus and polyomavirus capsids. | capsids of papilloma and polyoma viruses (papovavirus family) are composed of 72 pentameric capsomeres arranged on a skewed icosahedral lattice (triangulation number of seven, t = 7). cottontail rabbit papillomavirus (crpv) was reported previously to be a t = 7laevo (left-handed) structure, whereas human wart virus, simian virus 40, and murine polyomavirus were shown to be t = 7dextro (right-handed). the crpv structure determined by cryoelectron microscopy and image reconstruction was similar to ... | 1996 | 8656427 |
| solution structure of the dna-binding domain of a human papillomavirus e2 protein: evidence for flexible dna-binding regions. | the three-dimensional structure of the dna-binding domain of the e2 protein from human papillomavirus-31 was determined by using multidimensional heteronuclear nuclear magnetic resonance (nmr) spectroscopy. a total of 1429 nmr-derived distance and dihedral angle restraints were obtained for each of the 83-residue subunits of this symmetric dimer. the average root mean square deviations of 20 structures calculated using a distance geometry-simulated annealing protocol are 0.59 and 0.90 angstroms ... | 1996 | 8652551 |
| the human t-cell leukemia/lymphotropic virus type 1 p12i proteins bind the interleukin-2 receptor beta and gammac chains and affects their expression on the cell surface. | p12i is a small hydrophobic protein encoded by the human t-cell leukemia/lymphotropic virus type 1 (htlv-1) that interacts with the 16-kda component of the h+ vacuolar atpase and cooperates with bovine papillomavirus 1 e5 oncoprotein in cell transformation. just as an important step in e5 action appears to be its binding to the platelet-derived growth factor receptor, it was found that p12i binds specifically to both the beta and gamma(c) chains of the interleukin-2 receptor (il-2r). the il-2r b ... | 1996 | 8648694 |
| e5 oncoprotein transmembrane mutants dissociate fibroblast transforming activity from 16-kilodalton protein binding and platelet-derived growth factor receptor binding and phosphorylation. | the e5 oncoprotein of bovine papillomavirus type 1 is a 44-amino-acid, hydrophobic polypeptide which localizes predominantly in golgi membranes and appears to transform cells through the activation of tyrosine kinase growth factor receptors. in fibroblasts, e5 interacts with both the 16-kilodalton vacuolar atpase subunit and the platelet-derived growth factor receptor (pdgf-r) via its hydrophobic transmembrane domain and induces autophosphorylation of the receptor. to further analyze the correla ... | 1996 | 8642670 |
| status and transcriptional activity of a bovine-papillomavirus-i-based expression vector in a recombinant production cell lines. | 1996 | 8639276 | |
| activation of the endogenous p53 growth inhibitory pathway in hela cervical carcinoma cells by expression of the bovine papillomavirus e2 gene. | we previously showed that expression of the bovine papillomavirus (bpv) e2 gene results in a dramatic inhibition of the proliferation of several human cervical carcinoma cell lines, including hela cells which contain human papillomavirus (hpv) type 18 dna. we have assessed the status of endogenous g1 cell cycle regulatory proteins, including the tumor suppressor proteins, p53 and p105rb, in order to investigate growth regulatory pathways in hela cells following e2 expression. the p53 tumor suppr ... | 1996 | 8632901 |
| sp1 is critical for basal and e2-transactivated transcription from the bovine papillomavirus type 1 p89 promoter. | the bovine papillomavirus type 1 (bpv-1) long control region (lcr) contains at least three consensus binding sites for the transcription factor sp1 at nucleotides (nt) 7800, 7833 and 7854. a high basal-level p89 expression vector consisting of an origin-deleted lcr fused to the chloramphenicol acetyltransferase (cat) gene was utilized to determine the role of these sp1 sites in the regulation of transcription from the bpv-1 p89 promoter. the three sp1 sites were capable of binding sp1 in vitro. ... | 1996 | 8627222 |
| antigenicity of bovine papillomavirus type 1 (bpv-1) l1 virus-like particles compared with that of intact bpv-1 virions. | virus-like-particles (vlps) of various papillomavirus (pv) types have been produced by expressing recombinant l1 proteins in eukaryotic cells. although vlps have the same ultrastructural appearance as native virions and their immunogenicity appears to be similar, their antigenicity has not been carefully evaluated. for this reason, the antigenicity of intact bovine pv type 1 (bpv-1) virions was compared with that of bpv-1 recombinant l1 vlps by elisa using a well-characterized panel of polyclona ... | 1996 | 8627221 |
| virus-like particles of bovine papillomavirus type 4 in prophylactic and therapeutic immunization. | virus-like particles were produced in insect cells containing either the l1 and l2 capsid proteins of bovine papillomavirus type 4 (bpv-4) or only the l1 protein. both preparations of vlps proved to be extremely effective prophylactic vaccines. thirteen of 15 calves immunised with either l1-l2 vlps or l1-vlps were refractory to experimental challenge with high doses of bpv-4 and did not develop papillomas, while 9 of 10 control animals developed multiple oral papillomas. vlps were not efficient ... | 1996 | 8623552 |
| perturbation of the host cell cycle and dna replication by the bovine papillomavirus replication protein e1. | a stable cell line expressing the bovine papillomavirus e1 protein (c2e1) was compared with an e1 minus control line (cneo) to study the effects of e1 protein on host cell growth. c2e1 and cneo cells were synchronized either at mitosis or at the g1/s boundary by the cell cycle inhibitors nocodazole and mimosine, respectively. after release from the drug-induced cell cycle block, the progression through the succeeding stages of the cell cycle was temporally monitored using flow cytometry. in addi ... | 1996 | 8623531 |
| arsenic and chromium enhance transformation of bovine papillomavirus dna-transfected c3h/10t1/2 cells. | tumor promoters such as phorbol esters, teleocidin and okadaic acid increase the numbers of multilayered, transformed foci produced by bpv dna-transfected c3h/10t1/2 cells. we questioned whether arsenic and chromium, which are known human carcinogens also enhance transformation of bpv dna-transfected c3h/10t1/2 cells. cr(iii) potassium sulfate at 100 microm enhanced transformation by 1.4-fold, but cr(vi) as potassium chromate did not enhance transformation, although toxicity of potassium chromat ... | 1996 | 8616810 |
| mapping of hpv-11 e1 binding site and determination of other important cis elements for replication of the origin. | the viral proteins e1 and e2 are essential for the replication of the hpv-11 origin. we have now mapped the e1 binding site (e1bs) and show by mutation analysis that the e1bs and an adjoining poly(a)-rich region are necessary for efficient replication of the origin. we have also shown, using suboptimal levels of e1 protein, that enhancement of e1 binding by e2 partially protects the e1bs. finally, we show that e1 can enhance the binding of e2 even in the absence of the e1bs. | 1996 | 8614991 |
| pituitary-specific chromatin structure of the rat prolactin distal enhancer element. | the location of target dna sequences within chromatin may affect the ability of trans-acting factors to bind cis-elements and regulate gene transcription. to examine the effect of chromatin structure on the ability of the estrogen-estrogen receptor complex (e2r) to bind its respective dna binding element within the rat prolactin (rprl) gene and modulate rprl gene expression, we have developed cell lines derived from the rprl-expressing (rprl+) rat pituitary cell line gh3 and the rprl-non- expres ... | 1996 | 8604340 |
| stable expression of the reovirus mu2 protein in mouse l cells complements the growth of a reovirus ts mutant with a defect in its m1 gene. | reovirus mu2 protein was constitutively expressed in mammalian cells transfected with dicistronic constructs in which the reovirus m1 gene and the selectable neomycin-resistant gene (neo) were both driven by the same phosphoglycerate kinase promoter. translation of neo was initiated with the cap-independent translation initiation element from encephalomyocarditis virus. expression of mu2 protein was detected by mu2-specific antibody produced through immunization of rabbits with trp-e-mu2 fusion ... | 1996 | 8599234 |
| the bpv-1 e2 dna-contact helix cysteine is required for transcriptional activation but not replication in mammalian cells. | the papillomavirus e2 protein contains an amino-terminal region thought necessary and sufficient to support transcriptional activation and a carboxy-terminal region shown to direct sequence-specific dna binding and dimerization. a cysteine residue in the center of the e2 dna recognition helix is highly conserved among papillomavirus e2 proteins. mutations of this cysteine in bovine papillomavirus type 1 e2 to serine and glycine resulted in proteins which failed to activate e2-dependent promoters ... | 1996 | 8599215 |
| cis and trans requirements for stable episomal maintenance of the bpv-1 replicator. | papillomavirus genomes are maintained as multicopy nuclear plasmids in transformed cells. to address the mechanisms by which the viral dna is stably propagated in the transformed cells, we have constructed a cell line ch04.15 expressing constitutively the viral proteins e1 and e2, that are required for initiation of viral dna replication. we show that these viral proteins are necessary and sufficient for stable extrachromosomal replication. using the cell line ch04.15, we have shown that the bov ... | 1996 | 8598191 |
| [bovine papillomavirus vector]. | 1995 | 8584697 | |
| bpv e1 protein alters the kinetics of cell cycle entry of serum starved mouse fibroblasts. | a stable bovine papillomavirus e1 expressing cell line (c2e1) was used to investigate the effects of e1 protein on the requirement for growth factors during serum-induced reentry from quiescence to proliferation. flow cytometric bivariate dna/pcna analysis was utilized to study the expression of proliferating cell nuclear antigen (pcna) concomitant with this transition. c2e1 cells, unlike the control cells (cneo), were able to reenter the cell cycle when stimulated with low serum (1%). stimulati ... | 1995 | 8582248 |
| co-operative interaction between the initiator e1 and the transcriptional activator e2 is required for replicator specific dna replication of bovine papillomavirus in vivo and in vitro. | the e1 polypeptide from bovine papillomavirus binds to the origin of replication (ori) and possesses the activities attributed to initiator proteins. e1 is also the only viral protein required for replication in a cell-free replication system. replication in vivo, however, absolutely requires in addition the viral transcription factor e2. we demonstrate that the basis for this distinction between in vitro and in vivo requirements is the limited sequence specificity of the e1 protein. e1 and e2, ... | 1995 | 8557041 |
| the bovine papillomavirus type 1 e2 transactivator and repressor proteins use different nuclear localization signals. | the e2 gene of bovine papillomavirus type 1 encodes at least three nuclear phosphoproteins that regulate viral transcription and dna replication. all three proteins have a common c-terminal domain that has dna-binding and dimerization activities. a basic region in this domain forms an alpha helix which makes direct contact with the dna target. in this study, it is shown that in addition to its role in dna binding, this basic region functions as a nuclear localization signal both in the e2 dna-bi ... | 1996 | 8551571 |
| bovine papillomavirus type 4 in australia. | 1995 | 8534233 | |
| early phase in the infection of cultured cells with papillomavirus virions. | the fate of full bovine papillomavirus (bpv) virions and virus-like particles after binding to c127 or cv-1 cells was studied by electron microscopy and indirect immunofluorescence. after incubation at 4 degrees for 1 hr, bpv virions were found to be bound to the plasma membrane, and most viruses were absorbed by the cells after 30 min incubation at 37 degrees. ninety minutes after the virions had been bound to the plasma membrane, the uptake of the virions was completed and most of the antigen ... | 1995 | 8525612 |
| amino acids critical for the functions of the bovine papillomavirus type 1 e2 transactivator. | the n-terminal domain of the bovine papillomavirus type 1 e2 protein is important for viral dna replication, for transcriptional transactivation, and for interaction with the e1 protein. to determine which residues of this 200-amino-acid domain are important for these activities, single conservative amino acid substitutions have been generated in 17 residues that are invariant among all papillomavirus e2 proteins. the resulting mutated e2 proteins were tested for the ability to support viral dna ... | 1996 | 8523530 |
| e2 represses the late gene promoter of human papillomavirus type 8 at high concentrations by interfering with cellular factors. | the late gene promoter p7535 of the epidermodysplasia verruciformis-associated human papillomavirus type 8 (hpv8) is regulated by the viral e2 protein. transfection experiments performed with the human skin keratinocyte cell line rts3b and p7535 reporter plasmids revealed transactivation at low amounts and a repression of basal promoter activity at high amounts of e2 expression vector. this repression was promoter specific and correlated with the amount of transiently expressed e2 protein. mutat ... | 1996 | 8523515 |
| the p12i, p13ii, and p30ii proteins encoded by human t-cell leukemia/lymphotropic virus type i open reading frames i and ii are localized in three different cellular compartments. | three protein isoforms are encoded by the human t-cell leukemia/lymphotropic virus type i px region open reading frames (orf) i and ii through alternative splicing. both the singly and doubly spliced mrnas from orf i encode a single 12-kda protein (p12i), whereas two distinct proteins of 13 kda (p13ii) and 30 kda (p30ii) are encoded from the orf ii alternatively spliced mrna. because the p12i protein is very hydrophobic and poorly immunogenic, we genetically engineered its cdna by adding a short ... | 1993 | 8445734 |
| alanine mutagenesis of conserved residues in the platelet-derived growth factor family: identification of residues necessary for dimerization and transformation. | platelet-derived growth factor (pdgf) and vascular endothelial growth factor define a family of dimeric proteins characterized by eight conserved cysteine residues involved in disulfide bonds. thirteen non-cysteine residues conserved among the platelet-derived/vascular endothelial growth factors were individually mutated to alanine in v-sis/pdgf-b. in addition, five other residues flanking f148 were also mutated to alanine. the resulting mutants were assayed for transformation of nih3t3 cells, a ... | 1993 | 8437840 |
| the conserved c-terminal domain of the bovine papillomavirus e5 oncoprotein can associate with an alpha-adaptin-like molecule: a possible link between growth factor receptors and viral transformation. | the bovine papillomavirus e5 gene encodes an oncoprotein that can independently transform rodent fibroblasts. this small 44-amino-acid protein is thought to function through the activation of growth factor receptors. e5 activation of the epidermal growth factor receptor results in an increase in the number of activated receptors at the cell surface. this finding suggests that e5 may act by inhibiting the normal down regulation of activated epidermal growth factor receptor via coated pit-mediated ... | 1993 | 8413245 |
| interaction between bovine papillomavirus type 4 and cocarcinogens in the production of malignant tumours. | bovine fetal palatine tissue infected with bovine papillomavirus type 4 (bpv-4) was implanted subcutaneously in athymic nude mice. the implants developed into cysts containing papillomas essentially the same as those in the natural host. in order to investigate the interaction of cocarcinogens with bpv-4 in cell transformation, the virus-infected implants were exposed in vivo to either the tumour promoter 12-o-tetradecanoylphorbol-13-acetate (tpa) or the tumour initiator 7,12-dimethylbenz[a]-ant ... | 1993 | 8409951 |
| human papillomavirus and cutaneous warts in meat handlers. | the association of papillomavirus and hand warts in meat handlers was examined. human papillomavirus (hpv) dna was found in 23 (88%) of 26 cutaneous warts, with hpv 7 (27%) and a yet unidentified hpv (hpv x) (42%) being the predominant types. hpv 2 was found in two (7.5%) patients, and hpv 4 was found in three (11.5%) patients. no bovine papillomavirus sequences were detected. in most patients, the warts developed in less than 2 years after they started working with meat. a possible hpv transmis ... | 1993 | 8408588 |
| importance of the bovine papillomavirus p2443 promoter in the regulation of e2 and e5 expression. | the full-length bovine papillomavirus e2 gene product (e2ta), which has a direct role in dna replication and functions as a transcriptional activator, can be expressed from an unspliced mrna transcribed from the p2443 promoter or from spliced mrnas transcribed from other upstream promoters. the regulation of e2 expression from these promoters is still in question. in the background of wild-type protein coding sequences, this study identified the p2443 promoter as the major source of e2ta as well ... | 1993 | 8396681 |
| dna-binding domain of bovine papillomavirus type 1 e1 helicase: structural and functional aspects. | the e1 protein of bovine papillomavirus type 1 is a multifunctional enzyme required for papillomaviral dna replication. it assists in the initiation of replication both as a site-specific dna-binding protein and as a dna helicase. previous work has indicated that at limiting e1 concentrations, the e2 protein is required for efficient e1 binding to the replication origin. in this study, we have defined the domain of the e1 protein required for site-specific dna binding. experiments with a series ... | 1993 | 8396665 |
| dna of bovine papillomavirus type 1 and 2 in equine sarcoids: pcr detection and direct sequencing. | nucleotide sequences of bovine papillomavirus (bpv) dna amplified by the polymerase chain reaction (pcr) from samples of equine sarcoid skin tumours were determined. all naturally occurring sarcoids (n = 58 tumours from 32 horses and 2 donkeys) contained bpv-dna. all but 3 of the genome fragments belonged to the bpv type 1 strain (bpv-1); the remaining were bpv type 2. similar results were obtained with cutaneous bovine papillomas used as controls (n = 20). one of the horses, carrying 2 sarcoids ... | 1993 | 8394687 |
| cooperative dna binding of the bovine papillomavirus e2 transcriptional activator is antagonized by truncated e2 polypeptides. | cooperative dna binding of the bovine papillomavirus type 1 (bpv-1) e2 transcriptional activator (e2-ta) is thought to play a role in the transcriptional synergism of multiple e2-responsive dna elements (j. ham, n. dostatni, j.-m. gauthier, and m. yaniv, trends biochem. sci. 16:440-444, 1991). binding-equilibrium considerations show that such involvement is unlikely, thereby suggesting that the e2-ta cooperative capacity may have evolved to play other, different roles. the role of cooperative in ... | 1993 | 8394466 |
| differentiation-specific expression from the bovine papillomavirus type 1 p2443 and late promoters. | the papillomavirus life cycle is tightly linked with keratinocyte differentiation in squamous epithelia. vegetative viral dna replication begins in the spinous layer, while synthesis of capsid proteins and virus maturation is restricted to the most differentiated or granular layer of the epithelium. in this study, in situ hybridization of bovine fibropapillomas was used to demonstrate that the activity of two promoters of bovine papillomavirus type 1 (bpv-1) is regulated in a differentiation-spe ... | 1993 | 8394463 |
| transformation-specific interaction of the bovine papillomavirus e5 oncoprotein with the platelet-derived growth factor receptor transmembrane domain and the epidermal growth factor receptor cytoplasmic domain. | the bovine papillomavirus e5 transforming protein appears to activate both the epidermal growth factor receptor (egf-r) and the platelet-derived growth factor receptor (pdgf-r) by a ligand-independent mechanism. to further investigate the ability of e5 to activate receptors of different classes and to determine whether this stimulation occurs through the extracellular domain required for ligand activation, we constructed chimeric genes encoding pdgf-r and egf-r by interchanging the extracellular ... | 1993 | 8394451 |
| repression of bovine papillomavirus type 1 transcription by the e1 replication protein. | bovine papillomavirus type 1 (bpv-1) is the prototype virus for the study of papillomavirus gene regulation. the functions of the bpv-1 e2 proteins in transcriptional regulation have been well characterized. the bpv-1 e1 protein is required for viral dna replication and can bind to the origin of replication alone or in a complex with the e2 transactivator protein. in this study, we demonstrated that the bpv-1 e1 protein is also involved in transcriptional regulation. the e1 protein significantly ... | 1993 | 8394436 |
| a study from south india on the association between the papilloma virus and carcinoma of the penis. | specimens from 39 cases of squamous cell carcinoma of the penis were treated for the papilloma virus using the bovine papilloma virus antibody and the peroxidase-antiperoxidase technique. all 39 cases showed a viral antigen situated intranuclearly, intracytoplasmically or both intranuclearly and intracytoplasmically. no correlation could be seen between the presence of viral antigen and age of patient, duration of lesion, cell morphology and histological grade. the adjacent mucosa and skin were ... | 1993 | 8393502 |
| cooperative assembly of the bovine papilloma virus e1 and e2 proteins on the replication origin requires an intact e2 binding site. | using quantitative gel retardation assays the properties of the bovine papilloma virus (bpv) origin recognition protein e1 and the effect of the viral e2 protein on the binding of e1 to bpv origin dna were examined. as reported previously (seo, y.s., mueller, f., lusky, m., gibbs, e., kim, h.-y., phillips, b. and j. hurwitz (1993) proc. natl. acad. sci. u. s. a. 90, 2865-2869), the e1 protein binds specifically to dna sequences within the bpv origin (ori+) of replication. we also show that the p ... | 1993 | 8393453 |
| the acidic transcriptional activation domains of vp16 and p53 bind the cellular replication protein a and stimulate in vitro bpv-1 dna replication. | for papillomavirus dna replication, the e2 enhancer protein cooperatively assists in binding of the e1 helicase to the origin. we report that, at limiting e1 and e2 levels, the enhancer proteins gal4-vp16 and gal4-p53(1-73) stimulate bpv in vitro dna replication. this cell-free system was used to ascertain whether the acidic activation domains have a cellular target important for replication. cellular extracts were depleted of replication activity by passage through a vp16 affinity column. the p ... | 1993 | 8390328 |
| p3 promoter element of bovine papillomavirus. | the p3 promoter activity of bovine papillomavirus (bpv) and cis-acting dna element of p3 promoter required for transcription were examined using chloramphenicol acetyltransferase (cat) assay. the results show that p3 promoter is a very weak promoter compared to p2 promoter in bpv and e2 transactivator is required for the maximal transcription of p3 promoter in a bpv upstream regulatory region (urr)-dependent manner. deletion experiments by nuclease bal-31 were carried out to define p3 promoter e ... | 1993 | 8390322 |
| identification and characterization of novel promoters in the genome of human papillomavirus type 18. | most studies on the regulation of gene expression in human papillomaviruses (hpv) have focused on the promoter for the early genes e6 and e7. this promoter is located at the junction between the long control region and the e6 open reading frame. rna mapping studies have suggested that additional promoters may exist in other parts of the genome. in this study, we used a combination of transcription in vitro and an analysis of rna produced in vivo in transfected cells to identify three novel promo ... | 1993 | 8389929 |
| inhibition of cervical carcinoma cell line proliferation by the introduction of a bovine papillomavirus regulatory gene. | human papillomavirus (hpv) e6 and e7 oncogenes are expressed in the great majority of human cervical carcinomas, whereas the viral e2 regulatory gene is usually disrupted in these cancers. to investigate the roles of the papillomavirus e2 genes in the development and maintenance of cervical carcinoma, the bovine papillomavirus (bpv) e2 gene was acutely introduced into cervical carcinoma cell lines by infection with high-titer stocks of simian virus 40-based recombinant viruses. expression of the ... | 1993 | 8389903 |
| prophylactic and therapeutic vaccination against a mucosal papillomavirus. | papillomaviruses are ubiquitous dna viruses affecting humans and animals and causing a variety of tumours of mucosal and cutaneous epithelia. some of these lesions, particularly those affecting mucosal epithelia, can progress to squamous cell carcinomas. prevention or cure of viral infection would ultimately lead to a decrease in the incidence of papillomavirus-associated cancers. using recombinant proteins, we have developed prophylactic and therapeutic vaccines against bovine papillomavirus ty ... | 1993 | 8389809 |
| the e1 protein of bovine papilloma virus 1 is an atp-dependent dna helicase. | for efficient dna replication of papillomaviruses, only two viral-encoded proteins, e1 and e2, are required. other proteins and factors are provided by the host cell. e2 is an enhancer of both transcription and replication and is known to help e1 bind cooperatively to the origin of dna replication. e1 is sufficient for replication in extracts prepared from permissive cells, but the activity is enhanced by e2. here we show that purified e1 can act as an atp-dependent dna helicase. to measure this ... | 1993 | 8389467 |
| genetic definition of a new bovine papillomavirus type 1 open reading frame, e5b, that encodes a hydrophobic protein involved in altering host-cell protein processing. | we have previously observed that bovine papillomavirus type 1 (bpv-1) induces the appearance of five cellular proteins in c127 mouse fibroblasts, four of which appear to arise by altered processing of resident endoplasmic reticulum proteins. studies of various cell lines revealed that expression of the 3' end of the bpv early region was sufficient for induction of these changes. to identify the bpv gene responsible, we have utilized the simian virus 40 (sv40)/bpv-1 recombinant virus pava-1, whic ... | 1993 | 8388507 |
| enhanced degradation of p53 protein in hpv-6 and bpv-1 e6-immortalized human mammary epithelial cells. | normal mammary epithelial cells are efficiently immortalized by the e6 gene of human papillomavirus (hpv)-16, a virus commonly associated with cervical cancers. surprisingly, introduction of the e6 gene from hpv-6, which is rarely found in cervical cancer, or bovine papillomavirus (bpv)-1, into normal mammary cells resulted in the generation of immortal cell lines. the establishment of hpv-6 and bpv-1 e6-immortalized cells was less efficient and required a longer period in comparison to hpv-16 e ... | 1993 | 8387914 |
| behaviour of plasmid containing c4a2 repeats in s. cerevisiae and s. pombe. | plasmid, which combined the complete genome of bpv-i, yeast ars, leu yeast selectable marker gene, the neo selectable marker gene and inverted (c4a2)n telomeric repeat gene sequences cloned originally from tetrahymena thermophila, was constructed. it was introduced in either circular or linear form to saccharomyces cerevisiae or schizosaccharomyces pombe. although both yeasts could replicate the plasmid extrachromosomally, irrespective of whether it was introduced as a circular or linear structu ... | 1993 | 8387850 |
| t2g4 telomere repeats does not provide telomere function to a bpv-1 containing dna fragment in mouse c127 cells. | the ability of the (t2g4)n telomeric repeats to maintain a linear structure in an extrachromosomal replicating plasmid in mouse c127 cells was tested in a vector based on bovine papillomavirus type-1, ars, his3 and the neo genes. digestion with bamhi releases a bpv-1 containing fragment with a (t2g4)n repeats at each end which was introduced to yeast and microinjected into mouse c127 cells. while the linear construct was maintained as extrachromosomal structure in yeast cells, none of the result ... | 1993 | 8387849 |
| the 23-kilodalton e1 phosphoprotein of bovine papillomavirus type 1 is nonessential for stable plasmid replication in murine c127 cells. | the 23-kda protein encoded by the 5' segment of the e1 open reading frame of bovine papillomavirus type 1 (bpv1) was previously ascribed a negative regulatory function for the replication of viral plasmid dna. however, results from recent functional and biochemical studies do not readily support this genetic assignment. therefore, we have reassessed the role of this protein in papillomavirus dna replication by using a mutant of bpv1 which is unable to express this e1 protein. this mutant viral d ... | 1993 | 8386283 |
| characterization of human papillomavirus type 11 e1 and e2 proteins expressed in insect cells. | the study of human papillomavirus replication has been hampered by the lack of an in vitro system which reliably supports virus replication. recent results from the bovine papillomavirus (bpv) system indicate that the e1 and e2 proteins are the only viral gene products required for replication. by analogy with simian virus 40 large t antigen, e1 is thought to possess atpase and helicase activity, which may play a direct role in viral dna replication. the precise role of e2 is unclear, but it may ... | 1993 | 8386271 |
| synthesis and assembly of infectious bovine papillomavirus particles in vitro. | bovine papillomavirus type 1 (bpv-1) virions were produced in vitro using vaccinia virus (vv) recombinants expressing the bpv-1 l1 and l2 capsid proteins. particles morphologically resembling papillomaviruses were observed in the nucleus of cells infected with a vv recombinant for the bpv-1 l1 protein, and greater numbers of similar particles were seen in the nuclei of cells infected with a vv double recombinant for l1 and l2. virus-like particles (vlps) assembled in cells infected with the vv d ... | 1993 | 8385700 |
| identification of proteins binding to the f441 locus of polyomavirus b enhancer that are required for its activity in embryonic carcinoma cells. | a point mutation at nucleotide 5233 of the polyomavirus (a2 strain) enables it to overcome growth restriction in undifferentiated embryonal carcinoma cells. we analysed the binding of nuclear proteins from f9 cells to a 38 bp region that spans this site of mutation and encompasses two copies of the bovine papillomavirus core sequence, ccaccc, and characterized this domain by mutational analysis. our results showed that the f441 mutation creates a sequence motif which binds tef-1 or a tef-1-like ... | 1993 | 8385690 |
| sites of predicted stress-induced dna duplex destabilization occur preferentially at regulatory loci. | this paper describes a computational method to predict the sites on a dna molecule where imposed superhelical stresses destabilize the duplex. several dna sequences are analyzed in this way, including the pbr322 and cole1 plasmids, bacteriophage f1, and the polyoma and bovine papilloma virus genomes. superhelical destabilization in these molecules is predicted to occur at small numbers of discrete sites, most of which are within regulatory regions. the most destabilized sites include the termina ... | 1993 | 8385354 |
| bovine papilloma virus (bpv)-encoded e2 protein enhances binding of e1 protein to the bpv replication origin. | the replication of bovine papilloma virus (bpv) dna in vivo requires two viral-encoded proteins, e1 and e2, while all other proteins are derived from the host. we described previously the isolation of the e1 protein and showed that it contains multiple functions required for bpv dna replication. the bpv transcription factor e2 was shown by others to stimulate bpv dna replication in vitro. here, we present results that account for the role of the e2 protein. the e1 protein bound selectively to th ... | 1993 | 8385347 |