Publications

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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
antiapoptotic activity of bovine papilloma virus.	transformed fibroblasts have been recently shown to be sensitive for induction of apoptosis by tgf-beta-treated neighbouring untransformed cells. cells transformed by a variety of different transformation principles were regularly sensitive for intercellular induction of apoptosis, but fibroblasts transformed by bovine papillomavirus (bpv) represented a striking exception. in contrast to chemically transformed c127 cells, bpv-transformed c127 cells showed resistance against intercellular inducti ...	1996	21541598
bovine papillomavirus type 4.	papillomavirus induce benign tumours (papillomas) in a variety of animals. the papillomas generally regress but occassionally persist and may eventually progress to squamous cell carcinoma. one of the most extensively studies papillomaviruses is bovine papillomavirus type 4 (bpv4). bpv-4 induces papillomas of the upper alimentary canal which are at high risk of progressing to cancer in cattle eating bracken fern. in this review, several aspects of the biology of the virus are described and compa ...	1996	21541627
human papillomavirus type 16 e5 protein (review).	the association of certain human papillomavirus (hpv) types with malignancies of the anogenital tract is well established. the virus type most frequently associated with cellular transformation is hpv 16, as has been shown in epidemiological studies. its transforming capacity has also been demonstrated in many in vitro cell transformation experiments. the most potent oncogenes of hpv 16 are the e6 and e7 proteins, but the e5 protein, whose homologue is the main oncogene of bovine papillomavirus, ...	1997	21528338
methods for the construction of human papillomavirus vectors.	a number of vector systems have been developed for the delivery of therapeutic genes into cells (1). many viral vectors suffer from the disadvantage of random integration into the chromosome, making the expression of the cloned genes dependent on the chromosomal context of the inserted dna. papillomaviruses (pvs) are potentially important vector systems because of their extrachromosomal replication in target cells. the pvs are small dna viruses that infect humans and a wide range of animals. hum ...	1997	24493421
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
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
identification of papillomaviruses in scrapings from bovine warts by use of the polymerase chain reaction.		1997	9060144
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
virocrine transformation.		1997	9061007
synergistic transcriptional-activation by the papillomavirus e2 protein occurs after dna binding and correlates with a change in chromatin structure.	the papillomavirus e2 protein only activates transcription strongly when two or more of its binding-sites, each of which bind an e2 dimer, are present upstream of a minimal promoter. such synergy has been observed both in mammalian and yeast cells. in an attempt to understand the molecular basis of this synergy we carried out genomic footprinting to monitor the binding in vivo of native or mutant e2 proteins to different templates in yeast. we show that in vivo e2 binds to its site even under co ...	1997	9067604
dna binding and bending by the human papillomavirus type 16 e2 protein. recognition of an extended binding site.	the human papillomavirus (hpv) 16 e2 protein (he2) binds to four sites present upstream of the p97 promoter and regulates transcription of the viral e6 and e7 oncogenes. we have determined the relative binding constants for the interaction of the full-length he2 protein with these sites. our results show that he2 binds tightly to site 4, less tightly to sites 1 and 2, and weakly to site 3. similar results have previously been obtained using a c-terminal fragment of the he2 protein suggesting tha ...	1997	9079642
a papillomavirus e2 phosphorylation mutant exhibits normal transient replication and transcription but is defective in transformation and plasmid retention.	papillomavirus dna persists in infected cells as a nuclear plasmid, causing epithelial lesions in many hosts, including humans. the viral protein e2 is required for both replication and transcription to facilitate this persistence. bovine papillomavirus e2 protein is phosphorylated at two predominant sites. phosphorylation of one of these sites (serine 301) inhibits replication of the genome. using mass spectrometry and edman sequencing, we have mapped additional phosphorylation sites in tryptic ...	1997	9094639
functional interactions between papillomavirus e1 and e2 proteins.	dna replication of papillomaviruses requires the viral e1 and e2 proteins. these proteins bind cooperatively to the viral origin of replication (ori), which contains binding sites for both proteins, forming an e1-e2-ori complex which is essential for initiation of dna replication. to map the domains in e2 that are involved in the interaction with e1, we have used chimeric bovine papillomavirus (bpv)/human papillomavirus type 11 (hpv-11) e2 proteins. the results from this study show that both the ...	1997	9094661
the bovine papillomavirus e6 oncoprotein interacts with paxillin and disrupts the actin cytoskeleton.	the e6 oncoprotein of bovine papillomavirus type 1 (bpv-1) has been shown to transform cells through a p53-independent pathway, but its transforming mechanism is unknown. here we demonstrate in vitro and in vivo interactions between bpv-1 e6 and the focal adhesion protein paxillin. the ability of bpv-1 e6 to complex with paxillin correlated with its ability to transform; e6 mutant proteins impaired in their transformation function also were impaired in their abilities to bind paxillin. e6 bindin ...	1997	9114003
diagnostic phase antibody response to the human papillomavirus type 16 e2 protein is associated with successful treatment of genital hpv lesions with systemic interferon alpha-2b.	systemic interferon alpha-2b treatment reduces relapses of genital human papillomavirus (hpv) lesions in some but not all females. the aim of the present study was to investigate possible predictive pretreatment factors for the outcome of therapy.	1997	9126686
novel structural features of bovine papillomavirus capsid revealed by a three-dimensional reconstruction to 9 a resolution.	the three-dimensional structure of bovine papillomavirus has been determined to 9 a resolution by reconstruction of high resolution, low dose cryo-electron micrographs of quench-frozen virions. although hexavalent and pentavalent capsomeres form star-shaped pentamers of the major capsid protein l1, they have distinct high-resolution structures. most prominently, a 25 a hole in the centre of hexavalent capsomeres is occluded in the pentavalent capsomeres. this raises the possibility that the l2 m ...	1997	9145113
transformation by bovine papillomavirus type 1 e6 is independent of transcriptional activation by e6.	we have generated mutants of bovine papillomavirus type 1 e6 (be6) that are defective for transcriptional activation and have analyzed these mutants for transformation of contact-inhibited cells and association with the mammalian protein e6-ap. these be6 mutants demonstrate that transformation by be6 does not require transcriptional activation and that association of be6 with e6-ap is a function separable from transcriptional activation by be6. association of be6 with e6-ap appears to be necessa ...	1997	9151888
vaccination against papillomavirus in cattle.		1997	9167911
bovine papillomavirus e5 oncogene stimulates dna synthesis in c127 fibroblasts without general effects on growth factor responsive protein phosphorylations.	the bovine papillomavirus (bpv) transforming gene e5 is thought to modulate growth factor receptor function leading to a stimulation of growth factor signal transduction pathways. however, the influence of e5 on the range of receptor mediated changes in protein phosphorylation has not been addressed. we looked for the influence of e5 on dna synthesis as well as the phosphorylation of over 1000 cellular phosphoproteins in mouse c127 fibroblasts and subclones harboring wild type (id13)-, e5- mutan ...	1997	9191860
bovine papillomavirus type 1 dna replication: the transcriptional activator e2 acts in vitro as a specificity factor.	we previously devised cell-free conditions supporting efficient replication of bovine papillomavirus type 1 (bpv1) dna (c. bonne-andréa, s. santucci, and p. clertant, j. virol. 69:3201-3205, 1995): the use of highly active preparations of viral initiator protein e1, together with extract from a particular cell source, allowed the synthesis of complete dna circles through successive rounds of replication; this occurred in the absence of the viral transcriptional activator e2, required in vivo for ...	1997	9261405
cell-type-specific separate regulation of the e6 and e7 promoters of human papillomavirus type 6a by the viral transcription factor e2.	gene expression of human papillomaviruses (hpv) is tightly controlled by cellular factors and by the virally encoded e2 protein through binding to distinct sites within the regulatory noncoding region. while for the high-risk genital papillomaviruses a single promoter drives the expression of all early genes, a second promoter present in the e6 open reading frame of the low-risk hpv type 6 (hpv6) would allow an independent regulation of e6 and e7 oncogene expression. in this report, we provide t ...	1997	9261424
viral proteins of bovine papillomavirus type 4 during the development of alimentary canal tumours.	in cattle infection of the upper alimentary canal mucosa by bovine papillomavirus type 4 (bpv-4) results in the development of papillomas which can progress to cancer in animals fed on bracken fern. this paper describes a study of the cellular and subcellular distribution of a number of different bpv-4 products in experimentally-induced bpv-4 tumours. e8 and e4 proteins were detected solely as cytoplasmic antigens in the undifferentiated and differentiated layers of the papilloma, respectively; ...	1997	9265855
a peptide encoding a b-cell epitope from the n-terminus of the capsid protein l2 of bovine papillomavirus-4 prevents disease.	the first 200 n-terminus amino acids of the l2 capsid protein of bpv-4 (designated l2a) are an effective prophylactic vaccine against bpv-4 infection. vaccination with l2a induces the production of virus neutralizing antibodies, and when l2a antibodies are removed from immune sera, the sera lose their neutralization activity. l2a encodes three dominant b-cell epitopes, defined as epitope 1 (amino acids 101-120), epitope 2 (aa 131-151), and epitope 3 (aa 151-170). to investigate whether any of th ...	1997	9268157
adeno-associated virus rep78 inhibits oncogenic transformation of primary human keratinocytes by a human papillomavirus type 16-ras chimeric.	seroepidemiologic studies demonstrate that adeno-associated virus (aav) infection is negatively associated with cervical cancer. this inverse association may be due to an ability of aav to inhibit the role of human papillomavirus (hpv) in cervical carcinogenesis. in support of this hypothesis aav has been demonstrated to inhibit several papillomavirus types, including bovine papillomavirus type 1 and human papillomaviruses types 16 and 18 (hpv-16/18) in tissue culture. the aav-encoded rep78 prot ...	1997	9299265
mutational analysis of transcriptional activation by the bovine papillomavirus type 1 e6.	while the bovine papillomavirus type 1 (bpv-1) e6 induces tumorigenic transformation of murine c127 cells, it does not bind or promote the degradation of p53. we recently showed the cellular protein erc-55/e6bp binds bpv-1 e6 as well as the cancer-related human papillomavirus (hpv) e6 proteins. bpv-1 e6 also binds e6-ap, a ubiquitin ligase necessary for hpv e6-induced p53 degradation. we previously reported that the transforming activity of a set of bpv-1 e6 mutants correlated with their e6bp-bi ...	1997	9299614
linear b-cell epitopes in the n-terminus of l2 of bovine papillomavirus type 4.	the minor capsid protein l2 of bovine papillomavirus type 4 (bpv-4) is a very effective prophylactic vaccine which induces the production of virus neutralising antibodies and prevents virus-induced papillomatosis. the virus neutralising activity resides in the first 200 n-terminal amino acids of l2 (l2a). to further investigate the humoral immune response to l2, and the role it plays during infection and in prophylactic vaccination, the presentation of b-cell linear epitopes of l2a has been anal ...	1997	9300551
bovine papillomavirus type 5: partial sequence and comparison with other bovine papillomaviruses.	two restriction fragments of bovine papillomavirus type 5 (bpv5), of a genomic size of 1.6 and 1.2 kb were subcloned and sequenced. one of them seemed to correspond to the 3' end of the e1 open reading frame (orf) and the other to the region of the e7, e8 and 5' end of the e1 orf. alignments of these fragments with other bpvs showed that bpv5 is only distantly related to the other 5 bpvs.	1997	9311560
identification of amino acids in the transmembrane and juxtamembrane domains of the platelet-derived growth factor receptor required for productive interaction with the bovine papillomavirus e5 protein.	the bovine papillomavirus e5 protein forms a stable complex with the cellular platelet-derived growth factor (pdgf) beta receptor, resulting in receptor activation and cell transformation. amino acids in both the putative transmembrane domain and extracytoplasmic carboxyl-terminal domain of the e5 protein appear important for pdgf receptor binding and activation. previous analysis indicated that the transmembrane domain of the receptor was also required for complex formation and receptor activat ...	1997	9311809
bovine papillomavirus type 1 e1 and simian virus 40 large t antigen share regions of sequence similarity required for multiple functions.	the full-length product of the bovine papillomavirus type 1 (bpv-1) e1 translational open reading frame is required for viral dna replication in vivo and in vitro. e1 is a multifunctional protein whose properties include atp binding, acting as an atpase-dependent dna helicase, dna binding to the bpv-1 origin of viral dna replication, and association with the e2 transcriptional transactivator, e2ta, a second viral protein involved in dna replication. all of these properties are thought to be impo ...	1997	9311841
competitive binding of viral e2 protein and mammalian core-binding factor to transcriptional control sequences of human papillomavirus type 8 and bovine papillomavirus type 1.	the promoter p7535 of human papillomavirus type 8 and the promoter p7185 of bovine papillomavirus type 1 are negatively regulated by viral e2 proteins via the promoter proximal binding sites p2 and bs1, respectively. mutations of these e2 binding sites can reduce basal promoter activity. this suggests binding of a transcription-stimulating factor and may indicate that repression by e2 is due to competitive binding of viral and cellular proteins. a computer search revealed putative binding sites ...	1997	9311900
conserved interaction of the papillomavirus e2 transcriptional activator proteins with human and yeast tfiib proteins.	papillomavirus early gene expression is regulated by the virus gene-encoded e2 proteins. the best-characterized e2 protein, encoded by bovine papillomavirus type 1 (bpv-1), has been shown to interact with basal transcription factor iib (tfiib) and the tata binding protein basal transcription factor (n. m. rank and p. f. lambert, j. virol. 69:6323-6334, 1995). we demonstrate that the potent e2 transcriptional activator protein encoded by a gene of human pv type 16 also interacts with tfiib in vit ...	1997	9311902
papillomavirus is resistant to desiccation.	there is strong epidemiologic evidence for sexual transmission of high-risk genital human papillomavirus (hpv) types. however, it is unclear if infection may also be transmitted indirectly via fomites. to assess this possibility, the in vitro infectivity after desiccation was compared for pseudotype hpv-16 virions, a model for high-risk type genital hpv, and bovine papillomavirus type 1 (bpv-1), a papillomavirus known to be transmitted via fomites. the 2 viruses had similar resistance to desicca ...	1997	9333171
reconstitution of a functional bovine papillomavirus type 1 origin of replication reveals a modular tripartite replicon with an essential at-rich element.	a functional replication origin was reconstituted using oligonucleotide cassettes corresponding to three sequence subelements within the bovine papillomavirus type 1 (bpv-1) replication origin: the 23-bp at-rich region (atr), the 18-bp binding site for the viral replication initiator protein e1 (e1bs), and a binding site for the viral transcriptional transactivator and replication enhancer protein e2 (e2bs). replication of the reconstituted origin depended on heterologous expression of both the ...	1997	9356332
the role of exogenous p53 and e6 oncoproteins in in vitro transformation by bovine papillomavirus type 4 (bpv-4): significance of the absence of an e6 orf in the bpv-4 genome.	bovine papillomavirus type 4 (bpv-4) does not possess an e6 orf. the e6 oncoprotein of human papillomavirus (hpv) binds and degrades the tumour suppressor protein p53, thus contributing to tumour progression. since bpv-4 lacks e6, it is unknown how the virus evades the tumour suppressor properties of p53 in the induction of tumours of the gastrointestinal tract. mutations in the p53 gene have been detected both in papillomas and carcinomas, suggesting that p53 dysfunction plays a part in these n ...	1997	9367387
structural, functional, and protein binding analyses of bovine papillomavirus type 1 exonic splicing enhancers.	alternative splicing plays an important role in regulation of bovine papillomavirus type 1 (bpv-1) gene expression. we have recently identified in bpv-1 late pre-mrnas two purine-rich exonic splicing enhancers (se1 and se2) which also stimulate splicing of a drosophila doublesex (dsx) pre-mrna containing a suboptimal 3' splice site. in vivo studies now demonstrate that both se1 and se2 are required for preferential use of the bpv-1 nucleotide (nt) 3225 3' splice site in nonpermissive cells. dele ...	1997	9371566
functional interaction of a novel cellular protein with the papillomavirus e2 transactivation domain.	the transactivation domain (ad) of bovine papillomavirus type 1 e2 stimulates gene expression and dna replication. to identify cellular proteins that interact with this 215-amino-acid domain, we used a transactivation-defective mutant as bait in the yeast two-hybrid screen. in vitro and in vivo results demonstrate that the cdna of one plasmid isolated in this screen encodes a 37-kda nuclear protein that specifically binds to an 82-amino-acid segment within the e2 ad. mutants with point mutations ...	1997	9372953
gene transfer of the cd80 costimulatory molecule into ocular melanoma cells using a novel episomal vector.	the cd80 (b7.1) molecule, which is a necessary costimulatory signal for t-cell activation and proliferation, is a powerful inducer of antitumor immunity. in this study, primary human ocular melanoma cells were transfected with a novel vector (b45-neo episomal vector) containing the complementary dna (cdna) for human cd80 to determine if this vector system is useful for stimulating cd8+ t cells.	1997	9375572
nmr-based discovery of lead inhibitors that block dna binding of the human papillomavirus e2 protein.	the e2 protein is required for the replication of human papillomaviruses (hpvs), which are responsible for anogenital warts and cervical carcinomas. using an nmr-based screen, we tested compounds for binding to the dna-binding domain of the hpv-e2 protein. three classes of compounds were identified which bound to two distinct sites on the protein. biphenyl and biphenyl ether compounds containing a carboxylic acid bind to a site near the dna recognition helix and inhibit the binding of e2 to dna. ...	1997	9379433
the bovine papillomavirus e6 protein binds to the ld motif repeats of paxillin and blocks its interaction with vinculin and the focal adhesion kinase.	the bovine papillomavirus type 1 (bpv-1) e6 oncoprotein can transform fibroblasts and induce anchorage-independent growth and disassembly of the actin stress fibers. we have previously shown that the e6 protein interacts with the focal adhesion protein, paxillin, suggesting a direct role of e6 in the disruption of the actin cytoskeleton. we have now mapped the e6 binding sites on paxillin to the ld motif repeats region, which has been implicated in mediating paxillin binding to two other focal a ...	1997	9407131
papillomaviruses: progress for human and veterinary medicine.		1997	9414949
bovine papillomavirus and cancer.	bovine papillomavirus (bpv) induces papillomas of cutaneous or mucosal epithelia in cattle. the papillomas are benign tumours and generally regress, but occasionally persist and provide the focus for malignant transformation to squamous cell carcinoma, particularly in the presence of environmental cofactors. this has been experimentally demonstrated for bpv-2 and cancer of the urinary bladder, and bpv-4 and cancer of the upper alimentary canal in cattle feeding on bracken fern. in this review, s ...	1997	9414951
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
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
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
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
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
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
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
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
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
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
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
screening for bovine papillomavirus in peripheral blood cells of donkeys with and without sarcoids.	papillomaviral dna has been identified in peripheral blood cells of both cattle and humans with and without associated disease and it has been suggested that such cells may act as sites of viral latency. in order to investigate the possibility of latent papillomaviral infection in the aetiopathogenesis of the equine sarcoid, peripheral blood derived dna samples from 20 healthy and 34 sarcoid-affected donkeys were subject to polymerase chain reaction (pcr) using papillomaviral specific primers. a ...	1997	9491459
interaction of prion peptide huprp106-126 with nucleic acid.	synthetic prion peptide prp106-126 has been used as a model to understand prion diseases. the conformation of the peptide depends on the environmental conditions and it forms amyloid in vitro. the potential of this prion peptide to interact with nucleic acids has been studied using a fluorescent labelled nucleic acid by kinetic and equilibrium methods. a decrease in the fluorescence of the labelled dna induced by the peptide with time is observed which is ph, ionic strength and temperature depen ...	1997	9672613
two antibodies that neutralize papillomavirus by different mechanisms show distinct binding patterns at 13 a resolution.	complexes between bovine papillomavirus type 1 (bpv1) and examples of two sets of neutralizing, monoclonal antibodies (mab) to the major capsid protein (l1) were analyzed by low-dose cryo-electron microscopy and three-dimensional (3d) image reconstruction to 13 a resolution. mab #9 is representative of a set of neutralizing antibodies that can inhibit viral binding to the cell surface, while mab 5b6 is representative of a second set that efficiently neutralizes papillomaviruses without significa ...	1998	9680478
bpv-4 e8 transforms nih3t3 cells, up-regulates cyclin a and cyclin a-associated kinase activity and de-regulates expression of the cdk inhibitor p27kip1.	the e8 open reading frame of bovine papillomavirus type 4 (bpv-4) encodes a small (42 amino acid) hydrophobic polypeptide localized to cellular membranes and capable of conferring an anchorage-independent (ai) growth phenotype on primary bovine cells co-transfected with bpv-4 e7 orf and an activated ras gene. to further study the function of e8 independently of other viral gene products, we have expressed it in the murine fibroblast cell line, nih3t3. cells expressing e8 are capable of ai growth ...	1998	9690511
1h, 15n, and 13c nmr resonance assignments for the dna-binding domain of the bpv-1 e2 protein.		1998	9691287
functional interaction between the bovine papillomavirus virus type 1 replicative helicase e1 and cyclin e-cdk2.	we have found that the replicative helicase e1 of bovine papillomavirus type 1 (bpv-1) interacts with a key cell cycle regulator of s phase, the cyclin e-cdk2 kinase. the e1 helicase, which interacts with cyclin e and not with cdk2, presents the highest affinity for catalytically active kinase complexes. in addition, e1, cyclin e, and cdk2 expressed in xenopus egg extracts are quantitatively coimmunoprecipitated from crude extracts by either anti-cdk2 or anti-e1 antibodies. e1 protein is also a ...	1998	9696820
subpopulations of lymphocytes in cattle naturally infected with papillomavirus.	subpopulations of blood lymphocytes (cd2, cd4, cd8, wc1 and igm-mu chain) were evaluated in clinically manifested bovine papillomatosis. significantly lower numbers of cd2 (44.7%), cd4 (22.8%) and a lower ratio of cd4/cd8 (1.5) were found in animals with tumours compared to a group of cattle free of papillomas (62.3%, 34%, and 2.3, respectively). on the other hand, significantly higher numbers of gamma/delta+ t lymphocytes (9.6%) and of lymphocytes expressing igm molecules (35%) were observed in ...	1998	9704506
inhibition/stimulation of bovine papillomavirus by adeno-associated virus is time as well as multiplicity dependent.	infection by adeno-associated virus (aav) is associated with lower cervical cancer rates. we have been investigating the hypothesis that aav interacts with and inhibits the role of human papillomaviruses (hpv) in cervical cancer. we have been studying the response of bovine papillomavirus type 1 (bpv) oncogenic transformation and dna replication to aav as a prototype system. the aav rep 78 gene product is responsible for this inhibition. here, it is demonstrated that in two assay systems, focus ...	1998	9705917
the papillomavirus e6 proteins.	specific types of human papillomaviruses (hpv) are strongly associated with the development of cervical cancer. the e6 gene from cancer-related hpvs has exhibited functions in tumorigenesis, regulation of transcription, telomerase, and apoptosis. cancer-related hpvs e6 proteins bind the tumor suppressor p53 and promotes its degradation through an ubiquitin-dependent pathway. several additional cellular e6-binding proteins have recently been identified and implicated in playing roles in p53-indep ...	1998	9739758
bovine papillomavirus transmission and chromosomal aberrations: an experimental model.	enzootic haematuria and urinary bladder cancer in cattle are associated with feeding on bracken fern and bovine papillomavirus (bpv) infection. an increased rate of chromosomal aberrations in peripheral blood lymphocytes from chronically affected haematuric cows raised in bracken fern pastures has been reported, suggesting the presence of bpv in the peripheral blood of afflicted animals. the purpose of the present investigation was to examine the role of peripheral blood as a potential bpv-trans ...	1998	9747721
role of glutamine 17 of the bovine papillomavirus e5 protein in platelet-derived growth factor beta receptor activation and cell transformation.	the bovine papillomavirus e5 protein is a small, homodimeric transmembrane protein that forms a stable complex with the cellular platelet-derived growth factor (pdgf) beta receptor through transmembrane and juxtamembrane interactions, resulting in receptor activation and cell transformation. glutamine 17 in the transmembrane domain of the 44-amino-acid e5 protein is critical for complex formation and receptor activation, and we previously proposed that glutamine 17 forms a hydrogen bond with thr ...	1998	9765437
l1-specific protection from tumor challenge elicited by hpv16 virus-like particles.	a single injection of hpv16 l1 virus-like particles induced potent cd8-mediated protection from tumor challenge by c3 cells, a line derived from embryonic mouse cells transfected with the hpv16 genome. l1 rna, but not protein, was detected biochemically in c3 cells. these results indicate that low-level expression of hpv16 l1 can occur in proliferating cells and serve as a tumor vaccine target. although l1 expression is generally thought to be restricted to terminally differentiated epithelial c ...	1998	9792847
a pyrimidine-rich exonic splicing suppressor binds multiple rna splicing factors and inhibits spliceosome assembly.	the bovine papillomavirus type 1 (bpv-1) exonic splicing suppressor (ess) is juxtaposed immediately downstream of bpv-1 splicing enhancer 1 and negatively modulates selection of a suboptimal 3' splice site at nucleotide 3225. the present study demonstrates that this pyrimidine-rich ess inhibits utilization of upstream 3' splice sites by blocking early steps in spliceosome assembly. analysis of the proteins that bind to the ess showed that the u-rich 5' region binds u2af65 and polypyrimidine trac ...	1998	9826658
recruitment and loading of the e1 initiator protein: an atp-dependent process catalysed by a transcription factor.	initiation of dna replication critically depends on ori recognition as well as on catalytic activities of the initiator complex. for replication of papillomaviruses the catalytic activities for initiation are provided by the e1 protein. here, we show that the transcription factor e2 acts to assemble e1 into a complex active for ori distortion in two steps. first, cooperative dna binding of e1 and e2 generates a sequence-specific ori recognition complex. in the second atp-dependent step, e2 is di ...	1998	9843509
presence of papillomavirus-like dna sequences in cutaneous fibropapillomas of the goat udder.	papillomatous lesions were isolated from the mammary skin of goats and examined for evidence of papillomavirus (pv) infection by various criteria, including gross morphology, histology and dna hybridization. although some lesions showed gross papillomatous morphological and histological features similar to those caused by papillomavirus in other species, no viral particles were detected. reverse slot hybridization revealed cross-hybridization between dna extracted from goat mammary papillomas an ...	1998	9646460
the bpv-4 co-carcinogen quercetin induces cell cycle arrest and up-regulates transcription from the lcr of bpv-4.	bracken fern is the environmental co-carcinogen of bpv-4 in the induction of neoplasias of the upper alimentary canal of cattle. the flavonoid quercetin is one of the most potent and best characterised mutagens present in the fern. we have shown that transfection with bpv-4 dna and exposure to a single dose of quercetin leads to tumorigenic transformation of primary bovine cells. we now show that quercetin induces cell cycle arrest and up-regulates transcription from the bpv-4 long control regio ...	1998	9652740
p53 protein is a suppressor of papillomavirus dna amplificational replication.	p53 protein was able to block human and bovine papillomavirus dna amplificational replication while not interfering with epstein-barr virus orip once-per-cell cycle replication. oligomerization, intact dna-binding, replication protein a-binding, and proline-rich domains of the p53 protein were essential for efficient inhibition, while the n-terminal transcriptional activation and c-terminal regulatory domains were dispensable for the suppressor activity of the p53 protein. the inhibition of repl ...	1998	9658131
the papillomavirus e1 protein forms a dna-dependent hexameric complex with atpase and dna helicase activities.	the e1 protein from bovine papillomavirus has site-specific dna binding activity, dna helicase activity, and dna-dependent atpase activity consistent with the properties of an initiator protein. here we have identified and characterized a novel oligomeric form of e1 that is associated with the atpase and dna helicase activities and whose formation is strongly stimulated by single-stranded dna. this oligomeric form corresponds to a hexamer of e1.	1998	9658141
u1 snrnp inhibits pre-mrna polyadenylation through a direct interaction between u1 70k and poly(a) polymerase.	it has previously been shown in vivo that bovine papillomavirus represses its late gene expression via a 5' splice site sequence located upstream of the late polyadenylation signal. here, the mechanism of repression is determined by in vitro analysis. u1 snrnp binding to the 5' splice site results in inhibition of polyadenylation via a direct interaction with poly(a) polymerase (pap). although the inhibitory mechanism is similar to that used in u1a autoregulation, u1a within the u1 snrnp does no ...	1998	9659922
structural models of the bovine papillomavirus e5 protein.	the bovine papillomavirus e5 protein is thought to be a type ii integral membrane protein that exists as a disulfide-linked homodimer in transformed cells. polarized-infrared measurements show that the e5 dimer in membrane bilayers is largely alpha-helical and has a transmembrane orientation. computational searches of helix-helix conformations reveal two possible low-energy dimer structures. correlation of these results with previous mutagenesis studies on the e5 protein suggests how the e5 dime ...	1998	9849943
dna curvature and deformation in protein-dna complexes: a step in the right direction.		1998	9860938
structural code for dna recognition revealed in crystal structures of papillomavirus e2-dna targets.	transcriptional regulation in papillomaviruses depends on sequence-specific binding of the regulatory protein e2 to several sites in the viral genome. crystal structures of bovine papillomavirus e2 dna targets reveal a conformational variant of b-dna characterized by a roll-induced writhe and helical repeat of 10.5 bp per turn. a comparison between the free and the protein-bound dna demonstrates that the intrinsic structure of the dna regions contacted directly by the protein and the deformabili ...	1998	9860945
bovine papillomavirus e5 protein induces oligomerization and trans-phosphorylation of the platelet-derived growth factor beta receptor.	the bovine papillomavirus e5 protein is a 44-aa transmembrane protein that forms a stable complex with the cellular platelet-derived growth factor (pdgf) beta receptor and induces constitutive tyrosine phosphorylation and activation of the receptor, resulting in cell transformation. the e5 protein does not resemble pdgf, but rather activates the receptor in a ligand-independent fashion, thus providing a unique system to examine activation of receptor tyrosine kinases. here, we used a variety of ...	1998	9860953
mucosal immunisation with papillomavirus virus-like particles elicits systemic and mucosal immunity in mice.	it has been shown previously that recombinant virus-like particles (vlps) of papillomavirus can induce vlp-specific humoral and cellular immune responses following parenteral administration. to test whether mucosal administration of bovine papillomavirus type 1 (bpv1) vlps could produce mucosal as well as systemic immune responses to vlps, 50 micrograms chimeric bpv1 vlps containing an hpv16 e7 ctl epitope (bpvl1/e7 vlp) was administered intranasally to mice. after two immunisations, l1-specific ...	1998	9875315
crystal structure of the e2 dna-binding domain from human papillomavirus type 16: implications for its dna binding-site selection mechanism.	the crystal structure of the e2 dna-binding domain from the high-risk cervical cancer-associated strain human papillomavirus type 16 (hpv-16) is described here. the papillomavirus e2 proteins regulate transcription from all viral promoters and are required for the initiation of replication in vivo. they belong to a family of viral proteins that form dimeric beta-barrels and use surface alpha-helices for dna interaction. although all e2 proteins recognize the same consensus, palindromic dna seque ...	1998	9878365
structure of the e2 dna-binding domain from human papillomavirus serotype 31 at 2.4 a.	the papillomaviruses are a family of small double-stranded dna viruses which exclusively infect epithelial cells and stimulate the proliferation of those cells. a key protein within the papillomavirus life-cycle is known as the e2 (early 2) protein and is responsible for regulating viral transcription from all viral promoters as well as for replication of the papillomavirus genome in tandem with another protein known as e1. the e2 protein itself consists of three functional domains: an n-termina ...	1998	10089498
molecular replacement: the revival of the molecular fourier transform method.	the molecular fourier transform method, perhaps the first application of the molecular-replacement approach, used in the 1950s for the two-dimensional structure determination of small molecules, has been modernised for the efficient solution of complex structures. in the modern application of the molecular fourier transform (mft), the three-dimensional transform of the molecular model is calculated and fitting is achieved by rotating the weighted reciprocal lattice with respect to the calculated ...	1998	10089509
competition for dna binding sites between the short and long forms of e2 dimers underlies repression in bovine papillomavirus type 1 dna replication control.	papillomaviruses establish a long-term latency in vivo by maintaining their genomes as nuclear plasmids in proliferating cells. bovine papillomavirus type 1 encodes two proteins required for viral dna replication: the helicase e1 and the positive regulator e2. the homodimeric e2 is known to cooperatively bind to dna with e1 to form a preinitiation complex at the origin of dna replication. the virus also codes for two short forms of e2 that can repress viral functions when overexpressed, and at l ...	1998	9499046
bovine papillomavirus type 1 genomes and the e2 transactivator protein are closely associated with mitotic chromatin.	the bovine papillomavirus type 1 e2 transactivator protein is required for viral transcriptional regulation and dna replication and may be important for long-term episomal maintenance of viral genomes within replicating cells (m. piirsoo, e. ustav, t. mandel, a. stenlund, and m. ustav, embo j. 15:1-11, 1996). we have evidence that, in contrast to most other transcriptional transactivators, the e2 transactivator protein is associated with mitotic chromosomes in dividing cells. the shorter e2-tr a ...	1998	9499063
intercapsomeric disulfide bonds in papillomavirus assembly and disassembly.	in order to analyze bonding contacts that stabilize the virion or promote capsid assembly, bovine papillomavirus (bpv) virions were subjected to buffer conditions known to disrupt polyomavirus virions. at physiologic ionic strength, incubation with dithiothreitol (dtt), egta, or dtt plus egta did not disrupt bpv virions as determined by electron microscopy. however, incubation of virions with dtt rendered the bpv l1 protein susceptible to trypsin cleavage at its carboxy terminus and rendered the ...	1998	9499072
dna structure and flexibility in the sequence-specific binding of papillomavirus e2 proteins.	the papillomavirus e2 proteins are transcriptional regulators that bind to a consensus dna sequence accg nnnn cggt. multiple copies of this binding site are found in the viral genomes. the affinities of the naturally occurring binding sites for the e2 proteins are predominantly dependent upon the sequence of the nnnn spacer. the hierarchies of binding site affinities among the sites present in the viral genomes result in differential occupancy during the viral life-cycle. in turn, this different ...	1998	9500925