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B Safer

Publications and source records attributed to B Safer.

At least 37 records · Page 2Linked to original sources
PubMed1994

Sequence requirements for stable binding and function of Rep68 on the adeno-associated virus type 2 inverted terminal repeats.

Replication of the palindromic inverted terminal repeats (ITRs) of adeno-associated virus type 2 requires several functions of the viral nonstructural Rep proteins. These include binding to the ITR, nicking of the double-stranded replication intermediate at the terminal resolution site (trs), and then strand displacement and synthesis from the nick. This report demonstrates the ability of both recombinant fusion maltose-binding protein (MBP)-Rep68 delta produced in Escherichia coli and wild-type (wt) Rep68 to bind to a linear truncated form of the ITR, delta 57 ITR, with similar affinity as to the wt hairpin ITR. A dissociation constant for MBP-Rep68 delta of approximately 8 x 10(-10) M was determined for the wt ITR and delta 57 ITR probes. Truncation of delta 57 ITR to generate delta 28 ITR, which retains the GCTC repeat motif but not the trs, bound at least 10 times less efficiently than delta 57 ITR. Extension of delta 28 ITR with nonspecific sequence restored the ability of MBP-Rep68 delta to bind to delta 28 ITR. Thus, high-affinity binding would appear to require stabilization by flanking sequence as well as the intact GCTC repeat motif. Cleavage of the delta 57 ITR probe with DdeI, which truncates the flanking sequence and was previously shown to inhibit binding by Rep68, also inhibited the binding of MBP-Rep68 delta. The requirements for stable binding were further defined with a series of oligonucleotide probes which spanned the region protected by MBP-Rep78 in DNase I footprinting. The binding activity of either MBP-Rep68 delta or wt Rep68 to hairpin ITR or delta 57 ITR was indistinguishable. However, the binding activity of MBP-Rep68 delta to DNA does not appear to correlate with trs endonuclease activity. The nicking and covalent linkage of MBP-Rep68 delta to the nonhairpin delta 57 ITR was approximately 100-fold less efficient than its linkage to a hairpin-containing ITR. Therefore, although the hairpin portion of the ITR does not appear to play a role in recognition and stabilization of MBP-Rep68 delta binding, its presence does affect the trs cleavage activity of the protein.

ATP-Binding Cassette Transporters↗
PubMed1994

Biologically active Rep proteins of adeno-associated virus type 2 produced as fusion proteins in Escherichia coli.

Four Rep proteins are encoded by the human parvovirus adeno-associated virus type 2 (AAV). The two largest proteins, Rep68 and Rep78, have been shown in vitro to perform several activities related to AAV DNA replication. The Rep78 and Rep68 proteins are likely to be involved in the targeted integration of the AAV DNA into human chromosome 19, and the full characterization of these proteins is important for exploiting this phenomenon for the use of AAV as a vector for gene therapy. To obtain sufficient quantities for facilitating the characterization of the biochemical properties of the Rep proteins, the AAV rep open reading frame was cloned and expressed in Escherichia coli as a fusion protein with maltose-binding protein (MBP). Recombinant MBP-Rep68 and MBP-Rep78 proteins displayed the following activities reported for wild-type Rep proteins when assayed in vitro: (i) binding to the AAV inverted terminal repeat (ITR), (ii) helicase activity, (iii) site-specific (terminal resolution site) endonuclease activity, (iv) binding to a sequence within the integration locus for AAV DNA on human chromosome 19, and (v) stimulation of radiolabeling of DNA containing the AAV ITR in a cell extract. These five activities have been described for wild-type Rep produced from mammalian cell extracts. Furthermore, we recharacterized the sequence requirements for Rep binding to the ITR and found that only the A and A' regions are necessary, not the hairpin form of the ITR.

ATP-Binding Cassette Transporters↗
PubMed1994

Adeno-associated virus DNA replication in vitro: activation by a maltose binding protein/Rep 68 fusion protein.

The adeno-associated virus (AAV) nonstructural protein Rep 68 is required for viral DNA replication. An in vitro assay has been developed in which addition of Rep 68 to an extract from uninfected HeLa cells supports AAV DNA replication. In this paper, we report characterization of the replication process when a fusion of the maltose binding protein and Rep 68, expressed in Escherichia coli, was used in the assay. Replication was observed when the template was either linear double-stranded AAV DNA or a plasmid construct containing intact AAV DNA. When the recombinant plasmid construct was used as the template, there was replication of pBR322 DNA as well as the AAV DNA; however, linear pBR322 DNA was not replicated. When the plasmid construct was the template, replication appeared to initiate on the intact plasmid and led to separation of the AAV sequences from those of the vector, a process which has been termed rescue. There was no evidence that replication could initiate on the products of rescue. Rep 68 can make a site-specific nick 124 nucleotides from the 3' end of AAV DNA; the site of the nick has been called the terminal resolution site. Our data are most consistent with initiation occurring at the terminal resolution site and proceeding toward the 3' terminus. When the template was the plasmid construct, either elongation continued past the junction into pBR322 sequences or the newly synthesized sequence hairpinned, switched template strands, and replicated the AAV DNA. Replication was linear for 4 h, during which time 70% of the maximal synthesis took place. An additional finding was that the Rep fusion could resolve AAV dimer length duplex intermediates into monomer duplexes without DNA synthesis.

ATP-Binding Cassette Transporters↗
PubMed1993

A difference in the rate of ribosomal elongation balances the synthesis of eukaryotic translation initiation factor (eIF)-2 alpha and eIF-2 beta.

Eukaryotic translation initiation factor 2 (eIF-2) is a heterotrimer composed of three subunits designated alpha, beta, and gamma. These proteins exist in equimolar amounts in the cell and have not been detected as isolated subunits. Our research examines the basis of their balanced synthesis. Northern analysis of K562 cell mRNA revealed that eIF-2 beta was five times more abundant than eIF-2 alpha. However, immunoprecipitation of pulse-labeled K562 cells showed an equimolar rate of synthesis of eIF-2 alpha and -beta despite the 5-fold difference in the size of their mRNA pools. Addition of equal amounts of synthetic capped mRNA for eIF-2 alpha and eIF-2 beta to an in vitro translation reaction produced five times more eIF-2 alpha protein than eIF-2 beta. Determination of the polysome profile for alpha and beta mRNA in K562 cells indicated eIF-2 alpha was translated more efficiently than eIF-2 beta. Substitution of either the initiation codon context or the leader of the beta mRNA for that of alpha had only a minor effect on the translational efficiency of beta. Comparison of the rate of ribosomal elongation for the two mRNAs indicated that ribosomes associated with the beta mRNA elongate at a rate 4-fold less than that of eIF-2 alpha. Thus, the balanced translation of alpha and beta mRNA is primarily the result of a 4-fold difference in the rate of ribosomal elongation.

Base Sequence↗
PubMed1993

Regulation of eukaryotic translation initiation factor expression during T-cell activation.

Primary T-cells are metabolically quiescent, with little DNA, RNA or protein synthesis. Upon mitogenic stimulation the rate of protein synthesis increases 10-fold. We have studied the role of eIF-2 and eIF-4 alpha (eIF-4E) expression in the mechanism of translational activation. During this period, the levels of eIF-2 alpha and eIF-4 alpha mRNA increase some 50-fold. Similar to the increase in ribosomes and mRNA, the number of eIF-2 alpha, eIF-2 beta, and eIF-4 alpha molecules per cell also increase 2-3-fold. This suggests that in addition to an increase in the pool size of translational components, an additional mechanism exists which results in an increased efficiency of factor utilization. We have looked at initiation factor phosphorylation. We find that eIF-2 alpha does not undergo significant changes in its phosphorylation state nor is there a change in the efficiency of eIF-2 utilization. However, there is a rapid increase in the phosphorylation state of eIF-4 alpha which correlates with the rapid increase in translational activity. It thus appears there are 2 distinct components responsible for the translational activation of quiescent T-cells during mitogenic stimulation. The first is the phosphorylation of eIF-4 alpha, with a concomitant increase in the efficiency of eIF-4 alpha utilization. The second is an increase in the pool sizes of eIF-2 and eIF-4 alpha.

Eukaryotic Initiation Factor-2↗
PubMed1993

Purification of the human NF-E2 complex: cDNA cloning of the hematopoietic cell-specific subunit and evidence for an associated partner.

The human globin locus control region-binding protein, NF-E2, was purified by DNA affinity chromatography. Its tissue-specific component, p45 NF-E2, was cloned by use of a low-stringency library screen with murine p45 NF-E2 cDNA (N. C. Andrews, H. Erdjument-Bromage, M. B. Davidson, P. Tempst, and S. H. Orkin, Nature [London] 362:722-728, 1993). The human p45 NF-E2 gene was localized to chromosome 12q13 by fluorescent in situ hybridization. Human p45 NF-E2 and murine p45 NF-E2 are highly homologous basic region-leucine zipper (bZIP) proteins with identical DNA-binding domains. Immunoprecipitation experiments demonstrated that p45 NF-E2 is associated in vivo with an 18-kDa protein (p18). Because bZIP proteins bind DNA as dimers, we infer that native NF-E2 must be a heterodimer of 45- and 18-kDa subunits. Although AP-1 and CREB copurified with NF-E2, no evidence was found for heterodimer formation between p45 NF-E2 and proteins other than p18. Thus, p18 appears to be the sole specific partner of p45 NF-E2 in erythroid cells. Cloning of human p45 NF-E2 should permit studies of the role of NF-E2 in globin gene regulation and erythroid differentiation.

Amino Acid Sequence↗
PubMed1992

Regulation of translation initiation factor gene expression during human T cell activation.

Activation of quiescent T cells leads to a dramatic increase in the rate of protein synthesis. It is believed that this pronounced increase of protein synthesis is regulated primarily at the level of translational initiation. Although considerable evidence demonstrates that translational initiation can be regulated at the post-translational level by the phosphorylation/dephosphorylation of translation initiation factors (eIFs) such as eIF-4E and eIF-2 alpha, additional mechanisms of eIF gene expression may also play a role in the regulation of translation in quiescent cells and/or during their subsequent induction to enter the cell cycle. To address this issue, gene expression of eIF-2 alpha, -4E, and -4A was studied in quiescent human peripheral blood T cells following stimulation through the T cell receptor-CD3 complex. Quiescent T cells expressed low levels of eIF-2 alpha, -4E, and -4A mRNAs and proteins as compared to proliferating T cells. Activation of resting T cells resulted in a rapid increase (20-50-fold) in the levels of these three mRNAs. This increase did not require new protein synthesis. Furthermore, transcription rates of these three eIF genes showed only minor increase over the induction period as measured by nuclear run-on assays. Despite the rapid increase in initiation factor mRNA levels, increases in eIF protein levels lagged significantly behind. Western blot analysis also showed that the protein levels of the three eIFs were differentially increased. eIF-4A protein levels increased in proportion to the observed increase in cellular protein synthetic activity while the increases in eIF-4E and eIF-2 alpha proteins were proportionately less. The low levels of eIF proteins in quiescent T cells appear to correlate with low protein synthesis rate in such cells. The induction of eIF proteins by post-transcriptional/translational mechanisms appears to contribute to the pronounced stimulation of protein synthesis that occurs during T cell activation.

Animals↗
PubMed1992

Role of sequences within the first intron in the regulation of expression of eukaryotic initiation factor 2 alpha.

Resting human peripheral blood T cells synthesize proteins at very low rates and contain very low levels of eukaryotic initiation factor (eIF) 2 alpha mRNA. During mitogenic activation, the level of eIF-2 alpha mRNA increases at least 50-fold, an effect thought to be due primarily to intranuclear stabilization of the primary transcript (Cohen, R. B., Boal, T. R., and Safer, B. (1990) EMBO J. 9, 3831-3837). Analysis of sequences within the first intron revealed a region with homology to the "initiator" (Inr) sequence first described by Smale and Baltimore (Smale, S. T., and Baltimore, D. (1989) Cell 57, 103-113). This Inr element is positioned 450 bases downstream of the eIF-2 alpha promoter and is oriented to generate an overlapping antisense transcript. Deletion or mutation of the Inr element results in a reproducible 5-8-fold increase in the activity of an eIF-2 alpha promoter-driven CAT reporter gene and a corresponding 2.5-fold decrease in activity of an antisense driven luciferase reporter gene in vivo in 293 cells. In vitro transcription analysis also reveals antisense transcripts which depend on an intact Inr element and whose 5' ends map to sequences surrounding the Inr consensus sequence. A potential role for double-stranded RNA generated by these overlapping divergent transcription units in the regulation of eIF-2 alpha gene expression in T cells is suggested.

Base Sequence↗
PubMed1991

Interaction of CAP sequence site binding factor and transcription factor IID preceding and following binding to the adenovirus 2 major late promoter.

Interaction of cloned yeast, drosophila, and human transcription factor IID (yTFIID, dTFIID, and hTFIID, respectively) with the adenovirus 2 major late promoter (Ad2 MLP) confers a more limited pattern of DNase I protection than that obtained using highly purified native hTFIID (Hahn, S., Buratowski, S., Sharp, P. A. and Guarente, L. (1989) EMBO J. 8, 3379-3382; Van Dyke, M. W., and Sawadogo, M. (1990) Mol. Cell. Biol. 10, 3415-3420; Horikoshi, M., Wang, C.K., Fujii, H., Cromlish, J.A., Weil, P.A., and Roeder, R.G. (1989) Nature 341, 299-303; Peterson, M. G., Tanese, N., Pugh, B.F., and Tjian, R. (1990) Science 248, 1625-1630; Hoey, T., Dynlacht, B. D., Peterson, M.G., Pugh, B.F., and Tjian, R. (1990) Cell 61, 1179-1186). Since the mass of the cloned TFIIDs is considerably less than that of native hTFIID (27-38 kDa versus 120-140 kDa), it is considered likely that native hTFIID exists as a mixed heterodimer. We have recently identified, purified, and characterized a novel transcription factor that binds to the CAP site region (+1 to +23) of the Ad2 MLP. This CAP site binding factor, designated CBF, is required for optimal transcriptional activity. We now show that when bound to the Ad2 MLP, yTFIID and CBF interact to generate the extended pattern of DNase I protection conferred by native hTFIID. In addition, bound yTFIID and CBF interact such that the stability of the complex exceeds that of each factor bound alone. We also demonstrate the existence in nuclear extracts of a hTFIID and CBF heterodimer by the electrophoretic mobility shift analysis. CBF, therefore, may represent the first identified member of a large family of gene-specific TFIID-associated factors that are required for the regulated gene-specific expression of TFIID activity.

Adenoviruses, Human↗
PubMed1990

Identification and characterization of an adenovirus 2 major late promoter CAP sequence DNA-binding protein.

DNase I footprint analysis of the core adenovirus 2 (Ad2) major late promoter (MLP) has revealed distinct patterns of protection corresponding to the assembly of transcription components during transcriptional initiation (VanDyke, M. W., Sawadogo, M., and Roeder, R. G. (1989) Mol. Cell Biol. 7, 3371-3379). By using partially purified transcription factors, DNase I protection over the TATA box element and the CAP sequence was attributed to the binding of a single factor, TFIID. We have determined, however, that protection of the CAP region results from the binding of a novel factor, designated CAP-site binding factor (CBF), which is chromatographically and functionally distinct from TFIID. DNase I footprint analysis and gel electrophoresis mobility shift competition assays confirm that distinct polypeptides bind to the Ad2 MLP upstream promoter sequence, TATA box, and CAP sequences. When the CAP sequence is mutated, transcriptional activity of the Ad2 MLP is reduced both in vitro and in vivo. The decrease in transcriptional activity correlates with decreased CBF binding activity. Nuclear extracts depleted of CBF also exhibit reduced Ad2 MLP transcriptional activity. The addition of DNA affinity purified CBF, free of TFIID or major late transcription factor, restores the activity to control levels.

Adenoviruses, Human↗
PubMed1990

Increased eIF-2 alpha expression in mitogen-activated primary T lymphocytes.

G0 human T cells synthesize protein at low rates and contain very low levels of eIF-2 alpha mRNA. eIF-2 alpha plays a pivotal role in the earliest regulated steps of translation initiation. We examined eIF-2 alpha gene expression in normal human T cells stimulated with PHA. Nuclear run-on assays indicate low rates of eIF-2 alpha gene transcription in G0 cells and these change 2-fold with PHA treatment. Actinomycin D chase experiments show that the t1/2 of eIF-2 alpha mRNA is similar in G0 and PHA-treated T cells. Analysis of nuclear RNA with probes specific for eIF-2 alpha intron sequences shows that increased eIF-2 alpha expression after PHA treatment is largely due to intranuclear stabilization of the primary transcript. The increase in eIF-2 alpha mRNA does not require new protein synthesis. Hence, expression of this gene appears to be a part of the primary response program of T cells when they are exposed to mitogen.

Cell Nucleus↗
PubMed1989

Identification and characterization of a novel transcription factor participating in the expression of eukaryotic initiation factor 2 alpha.

We have recently cloned and characterized the promoter region of the gene encoding eukaryotic initiation factor 2 alpha (eIF-2 alpha) to identify regulatory elements of this housekeeping gene. We compared the location of DNase I-hypersensitive (HS) sites with the distribution of protein-binding sites as revealed by footprint analysis. The eIF-2 alpha promoter contains four upstream DNase I-HS sites extending from -650 to -40 base pairs and a fifth downstream site near the first intron-exon junction. In vitro DNase I footprint analysis shows eight distinct DNA-protein interactions organized into clusters that correspond well with the distribution of the five HS sites. None of the protected regions, however, shares obvious sequence homology with the binding sites of known regulatory factors. To initiate our analysis of factors required for eIF-2 alpha expression, selected a CAP-proximal element shown by in vivo methylation protection analysis to bind a potential regulatory factor. A striking feature of this element is its palindrome sequences and eight-base pair direct repeats. We have purified to near homogeneity a 66-68-kDa protein that binds to this region and have designated it alpha-PAL. The alpha-PAL-binding site extends from -74 to -10. By methylation protection analysis and mobility shift assay, the alpha-PAL-binding site is shown to be two adjacent sites, one with high and one with lower affinity, which bind alpha-PAL in a noncooperative manner. When the high affinity binding site is cloned upstream of the adenovirus 2 core promoter, in vitro transcription is stimulated 2-3-fold. When linked to a CAT reporter gene, activity of the eIF-2 alpha promoter shows an approximate 2-fold dependence on the alpha-PAL element.

Base Sequence↗
PubMed1989

Isolation and characterization of the promoter and flanking regions of the gene encoding the human protein-synthesis-initiation factor 2 alpha.

The promoter region of the gene (eIF-2 alpha) for eukaryotic initiation factor 2 alpha (eIF-2 alpha) was isolated from a human genomic library and its structure was determined by restriction mapping and nucleotide (nt) sequence analysis. The promoter region and twelve in vivo transcriptional start points (tsp) have been identified by endonuclease S1 mapping and their location confirmed by primer-extension analysis, using RNA isolated from human cells. The untranslated leader is 102 to 140 nt long depending upon the tsp, and the 5' region of the mRNA has the potential for forming stable stem-loop structures. The nt sequence of the regions upstream and downstream from the tsp contains neither a 'TATA box' nor a 'CAAT box', but does contain several direct and inverted repeats, as well as palindromic sequences near the tsp. In addition, multiple consensus binding sites for a wide variety of regulatory proteins are present throughout upstream and downstream tsp-flanking regions.

Base Sequence↗
PubMed1989

Reduced activity of the interferon-induced double-stranded RNA-dependent protein kinase during a heat shock stress.

Previous studies have shown that the antiviral response induced by interferon in murine cells could be degraded after a heat shock. Here we have confirmed that a similar effect occurs also in interferon-treated human HeLa cells subjected to a heat shock. In addition, we have investigated the fate of the interferon-induced, double-stranded RNA-dependent protein kinase in heat-shocked cells. This protein kinase is a Mr 68,000 protein (p68 kinase) which, when autophosphorylated, catalyzes phosphorylation of the protein synthesis eukaryotic initiation factor-2, thus mediating inhibition of protein synthesis. After heat shock of interferon-treated HeLa cells, the double-stranded RNA-dependent autophosphorylation of p68 kinase in cytoplasmic extracts is greatly reduced whereas the phosphorylation of other cellular proteins is not affected. In vivo, autophosphorylation of p68 kinase is also reduced in heat-shocked cells whereas there is no apparent effect on the phosphorylation state of other proteins. In such cells, the interferon-mediated antiviral response becomes modified according to the virus challenge, i.e. these cells remain resistant to vesicular stomatitis virus but become partially sensitive to encephalomyocarditis virus (EMCV) infection. The reduction in the activity of p68 kinase is due to its reduced nonionic detergent solubility occurring during the heat shock period. The resultant reduced detergent extractibility of p68 kinase is dependent on the intensity of the thermal stress. In contrast to the effect after a heat shock, arsenite treatment of interferon-treated HeLa cells induces heat shock proteins, but neither modifies the antiviral response nor affects the extractibility of p68 kinase. These results indicate that the degradation of the anti-EMCV response and reduced p68 kinase activity occur in response to heat treatment independently of the induction of heat shock proteins. The role of p68 kinase in the mechanism of the antiviral response against EMCV and vesicular stomatitis virus is discussed.

2',5'-Oligoadenylate Synthetase↗
PubMed1989

The cellular 68,000-Mr protein kinase is highly autophosphorylated and activated yet significantly degraded during poliovirus infection: implications for translational regulation.

We investigated the possible translational regulatory roles played by the interferon-induced, double-stranded-RNA-activated protein kinase (P68) and its natural substrate, eucaryotic initiation factor 2 (eIF-2), in poliovirus-infected cells. We demonstrated that protein kinase P68 was both highly autophosphorylated and activated during poliovirus infection. In accordance with these results, immunoprecipitation analysis revealed that phosphorylation of the endogenous eIF-2 alpha subunit also increased in poliovirus-infected cells. We found that double-stranded RNA synthesized during infection likely induced the high levels of P68 autophosphorylation. To determine whether the increase in kinase activity also could be attributed to induction of P68 synthesis, physical levels of protein kinase were measured. It was unexpectedly found that P68 protein levels did not increase but rather dramatically declined in poliovirus-infected cells. Pulse-chase experiments confirmed that the protein kinase was significantly degraded during virus infection. We corroborated our in vivo observations by developing an in vitro assay for P68 degradation using cell extracts. The possible consequences of P68 degradation and increased eIF-2 alpha phosphorylation for protein synthesis regulation in poliovirus-infected cells are discussed.

Enzyme Activation↗
PubMed1989

Functional dissection of adenovirus VAI RNA.

During the course of adenovirus infection, the VAI RNA protects the translation apparatus of host cells by preventing the activation of host double-stranded RNA-activated protein kinase, which phosphorylates and thereby inactivates the protein synthesis initiation factor eIF-2. In the absence of VAI RNA, protein synthesis is drastically inhibited at late times in infected cells. The experimentally derived secondary structure of VAI RNA consists of two extended base-paired regions, stems I and III, which are joined by a short base-paired region, stem II, at the center. Stems I and II are joined by a small loop, A, and stem III contains a hairpin loop, B. At the center of the molecule and at the 3' side, stems II and III are connected by a short stem-loop (stem IV and hairpin loop C). A fourth, minor loop, D, exists between stems II and IV. To determine sequences and domains critical for function within this VAI RNA structure, we have constructed adenovirus mutants with linker-scan substitution mutations in defined regions of the molecule. Cells infected with these mutants were analyzed for polypeptide synthesis, virus yield, and eIF-2 alpha kinase activity. Our results showed that disruption of base-paired regions in the distal parts of the longest stems, I and III, did not affect function, whereas mutations causing structural perturbations in the central part of the molecule containing stem II, the proximal part of stem III, and the central short stem-loop led to loss of function. Surprisingly, one substitution mutant, sub742, although dramatically perturbing the integrity of the structure of this central portion, showed a wild-type phenotype, suggesting that an RNA with an alternate secondary structure is functional. On the basis of sensitivity to single-strand-specific RNases, we can derive a novel secondary structure for the mutant RNA in which a portion of the sequences may fold to form a structure that resembles the central part of the wild-type molecule, which suggests that only the short stem-loop located in the center of the molecule and the adjoining base-paired regions may define the functional domain. These results also imply that only a portion of the VAI RNA structure may be recognized by the host factor(s).

Adenoviruses, Human↗
PubMed1988

Identification of a downstream sequence and binding protein that regulate adenovirus major late promoter transcription in vitro.

Gel electrophoresis mobility shift and DNase I footprint assays detect a cellular nuclear protein in extracts made from uninfected human cells which binds to a downstream promoter sequence (DPS) in the human adenovirus 2 major late promoter. By DNase I footprint and mutation analyses, we have determined that this new regulatory element extends from positions +146 to +165 (relative to the cap site at position +1). We show by UV cross-linking that a 40-kDa polypeptide specifically binds to this region. Mutations within the DPS which decrease protein binding by 80-90% also cause a 2.5-3-fold decrease in in vitro major late promoter transcription efficiency. Alteration of the template in the 5'-flanking region of the DPS does not affect nuclear protein binding or transcription efficiency. Interestingly, a T----G transversion at position +160 which increases protein binding also impairs promoter activity.

Adenoviruses, Human↗