1
|
Kala M, Babok S, Mikhailava N, Piirsoo M, Piirsoo A. The POU-HD TFs impede the replication efficiency of several human papillomavirus genomes. Virol J 2024; 21:54. [PMID: 38444021 PMCID: PMC10916165 DOI: 10.1186/s12985-024-02334-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Accepted: 02/28/2024] [Indexed: 03/07/2024] Open
Abstract
Human papillomavirus (HPV) is a double-stranded DNA virus that infects cutaneous and mucosal epithelial cells. HPV replication initiates at the origin (ori), located within a noncoding region near the major early promoter. Only two viral proteins, E1 and E2, are essential for replication, with the host cell contributing other necessary factors. However, the role of host cell proteins in regulating HPV replication remains poorly understood. While several binding sites for cellular transcription factors (TFs), such as POU-HD proteins, have been mapped in the regulatory region, their functional importance is unclear. Some POU-HD TFs have been shown to influence replication in a system where E1 and E2 are provided exogenously. In this study, we investigated the impact of several POU-HD TFs on the replication of the HPV5, HPV11, and HPV18 genomes in U2OS cells and human primary keratinocytes. We demonstrated that OCT1, OCT6, BRN5A, and SKN1A are expressed in HPV host cells and that their overexpression inhibits HPV genome replication, whereas knocking down OCT1 had a positive effect. Using the replication-deficient HPV18-E1- genome, we demonstrated that OCT1-mediated inhibition of HPV replication involves modulation of HPV early promoters controlling E1 and E2 expression. Moreover, using Oct6 mutants deficient either in DNA binding or transcriptional regulation, we showed that the inhibition of HPV18 replication is solely dependent on Oct6's DNA binding activity. Our study highlights the complex regulatory roles of POU-HD factors in the HPV replication.
Collapse
Affiliation(s)
- Martin Kala
- Institute of Technology, University of Tartu, Tartu, Estonia
| | - Sofiya Babok
- Institute of Technology, University of Tartu, Tartu, Estonia
| | - Nika Mikhailava
- Institute of Technology, University of Tartu, Tartu, Estonia
| | - Marko Piirsoo
- Institute of Technology, University of Tartu, Tartu, Estonia
| | - Alla Piirsoo
- Institute of Technology, University of Tartu, Tartu, Estonia.
| |
Collapse
|
2
|
Hsu CYM, Uludağ H. Nucleic-acid based gene therapeutics: delivery challenges and modular design of nonviral gene carriers and expression cassettes to overcome intracellular barriers for sustained targeted expression. J Drug Target 2012; 20:301-28. [PMID: 22303844 DOI: 10.3109/1061186x.2012.655247] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The delivery of nucleic acid molecules into cells to alter physiological functions at the genetic level is a powerful approach to treat a wide range of inherited and acquired disorders. Biocompatible materials such as cationic polymers, lipids, and peptides are being explored as safer alternatives to viral gene carriers. However, the comparatively low efficiency of nonviral carriers currently hampers their translation into clinical settings. Controlling the size and stability of carrier/nucleic acid complexes is one of the primary hurdles as the physicochemical properties of the complexes can define the uptake pathways, which dictate intracellular routing, endosomal processing, and nucleocytoplasmic transport. In addition to nuclear import, subnuclear trafficking, posttranscriptional events, and immune responses can further limit transfection efficiency. Chemical moieties, reactive linkers or signal peptide have been conjugated to carriers to prevent aggregation, induce membrane destabilization and localize to subcellular compartments. Genetic elements can be inserted into the expression cassette to facilitate nuclear targeting, delimit expression to targeted tissue, and modulate transgene expression. The modular option afforded by both gene carriers and expression cassettes provides a two-tier multicomponent delivery system that can be optimized for targeted gene delivery in a variety of settings.
Collapse
Affiliation(s)
- Charlie Yu Ming Hsu
- Department of Biomedical Engineering, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Cananda
| | | |
Collapse
|
3
|
Abstract
Hox proteins are well-known as developmental transcription factors controlling cell and tissue identity, but recent findings suggest that they are also part of the cell replication machinery. Hox-mediated control of transcription and replication may ensure coordinated control of cell growth and differentiation, two processes that need to be tightly and precisely coordinated to allow proper organ formation and patterning. In this review we summarize the available data linking Hox proteins to the replication machinery and discuss the developmental and pathological implications of this new facet of Hox protein function.
Collapse
Affiliation(s)
- Benoit Miotto
- UMR7216 Epigénétique et Destin Cellulaire, CNRS, Université Paris 7, Paris, France.
| | | |
Collapse
|
4
|
Dobson SE, Augustijn KD, Brannigan JA, Schnick C, Janse CJ, Dodson EJ, Waters AP, Wilkinson AJ. The crystal structures of macrophage migration inhibitory factor from Plasmodium falciparum and Plasmodium berghei. Protein Sci 2010; 18:2578-91. [PMID: 19827093 PMCID: PMC2798171 DOI: 10.1002/pro.263] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Malaria, caused by Plasmodium falciparum and related parasites, is responsible for millions of deaths each year, mainly from complications arising from the blood stages of its life cycle. Macrophage migration inhibitory factor (MIF), a protein expressed by the parasite during these stages, has been characterized in mammals as a cytokine involved in a broad spectrum of immune responses. It also possesses two catalytic activities, a tautomerase and an oxidoreductase, though the physiological significance of neither reaction is known. Here, we have determined the crystal structure of MIF from two malaria parasites, Plasmodium falciparum and Plasmodium berghei at 2.2 Å and 1.8 Å, respectively. The structures have an α/β fold and each reveals a trimer, in agreement with the results of analytical ultracentrifugation. We observed open and closed active sites, these being distinguished by movements of proline-1, the catalytic base in the tautomerase reaction. These states correlate with the covalent modification of cysteine 2 to form a mercaptoethanol adduct, an observation confirmed by mass spectrometry. The Plasmodium MIFs have a different pattern of conserved cysteine residues to the mammalian MIFs and the side chain of Cys58, which is implicated in the oxidoreductase activity, is buried. This observation and the evident redox reactivity of Cys2 suggest quite different oxidoreductase characteristics. Finally, we show in pull-down assays that Plasmodium MIF binds to the cell surface receptor CD74, a known mammalian MIF receptor implying that parasite MIF has the ability to interfere with, or modulate, host MIF activity through a competitive binding mechanism.
Collapse
Affiliation(s)
- Sarah E Dobson
- Structural Biology Laboratory, Department of Chemistry, University of York, York YO10 5YW, United Kingdom
| | | | | | | | | | | | | | | |
Collapse
|
5
|
Hama S, Akita H, Iida S, Mizuguchi H, Harashima H. Quantitative and mechanism-based investigation of post-nuclear delivery events between adenovirus and lipoplex. Nucleic Acids Res 2007; 35:1533-43. [PMID: 17287293 PMCID: PMC1865055 DOI: 10.1093/nar/gkl1165] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Quantitative and mechanism-based information on differences in transfection efficiency between viral and non-viral vectors would be highly useful for improving the effectiveness of non-viral vectors. A previous quantitative comparison of intracellular trafficking between adenovirus and LipofectAMINE PLUS (LFN) revealed that the three orders of magnitude lower transfection efficiency of LFN was dominantly rate limited by the post-nuclear delivery process. In the present study, the contribution of transcription and translation processes to the overall differences in the transgene expression efficiency of nucleus-delivered DNA was independently evaluated by quantifying mRNA. As a result, transcription efficiency (Etranscript) of LFN, denoted as transgene expression divided by the amount of nuclear pDNA was about 16 times less than that for adenovirus. Furthermore, translation efficiency (Etranslate), denoted as transfection activity divided by mRNA expression was approximately 460 times less in LFN. Imaging of the decondensed form of DNA by in situ hybridization revealed that poor decondensation efficiency of LFN is involved in the inferior Etranscript. Moreover, the inferior translation efficiency (Etranslate) of LFN was mainly due to electrostatic interactions between LFN and mRNA. Collectively, an improvement in nuclear decondensation and the diminution of the interaction between vector and mRNA is essential for the development of new generations of non-viral vectors.
Collapse
Affiliation(s)
- Susumu Hama
- Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo, Hokkaido 060-0812, Japan, Laboratory of Gene Transfer and Regulation, National Institute of Biomedical Innovation, Osaka 567-0085, Japan and CREST, Japan Science and Technology Corporation (JST), Japan
| | - Hidetaka Akita
- Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo, Hokkaido 060-0812, Japan, Laboratory of Gene Transfer and Regulation, National Institute of Biomedical Innovation, Osaka 567-0085, Japan and CREST, Japan Science and Technology Corporation (JST), Japan
| | - Shinya Iida
- Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo, Hokkaido 060-0812, Japan, Laboratory of Gene Transfer and Regulation, National Institute of Biomedical Innovation, Osaka 567-0085, Japan and CREST, Japan Science and Technology Corporation (JST), Japan
| | - Hiroyuki Mizuguchi
- Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo, Hokkaido 060-0812, Japan, Laboratory of Gene Transfer and Regulation, National Institute of Biomedical Innovation, Osaka 567-0085, Japan and CREST, Japan Science and Technology Corporation (JST), Japan
| | - Hideyoshi Harashima
- Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo, Hokkaido 060-0812, Japan, Laboratory of Gene Transfer and Regulation, National Institute of Biomedical Innovation, Osaka 567-0085, Japan and CREST, Japan Science and Technology Corporation (JST), Japan
- *To whom correspondence should be addressed. +81 11 706 3919+81 11 706 4879
| |
Collapse
|
6
|
Mesplède T, Island ML, Christeff N, Petek F, Doly J, Navarro S. The POU transcription factor Oct-1 represses virus-induced interferon A gene expression. Mol Cell Biol 2005; 25:8717-31. [PMID: 16166650 PMCID: PMC1265735 DOI: 10.1128/mcb.25.19.8717-8731.2005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Alpha interferon (IFN-alpha) and IFN-beta are able to interfere with viral infection. They exert a vast array of biologic functions, including growth arrest, cell differentiation, and immune system regulation. This regulation extends from innate immunity to cellular and humoral adaptive immune responses. A strict control of expression is needed to prevent detrimental effects of unregulated IFN. Multiple IFN-A subtypes are coordinately induced in human and mouse cells infected by virus and exhibit differences in expression of their individual mRNAs. We demonstrated that the weakly expressed IFN-A11 gene is negatively regulated after viral infection, due to a distal negative regulatory element, binding homeoprotein pituitary homeobox 1 (Pitx1). Here we show that the POU protein Oct-1 binds in vitro and in vivo to the IFN-A11 promoter and represses IFN-A expression upon interferon regulatory factor overexpression. Furthermore, we show that Oct-1-deficient MEFs exhibit increased in vivo IFN-A gene expression and increased antiviral activity. Finally, the IFN-A expression pattern is modified in Oct-1-deficient MEFs. The broad representation of effective and potent octamer-like sequences within IFN-A promoters suggests an important role for Oct-1 in IFN-A regulation.
Collapse
Affiliation(s)
- Thibault Mesplède
- Laboratoire de Régulation de la Transcription et Maladies Génétiques, CNRS, UPR 2228, UFR Biomédicale des Saints-Pères, Université René Descartes, 45 Rue des Saints-Pères, 75270 Paris Cedex 06, France
| | | | | | | | | | | |
Collapse
|
7
|
Mysiak ME, Wyman C, Holthuizen PE, van der Vliet PC. NFI and Oct-1 bend the Ad5 origin in the same direction leading to optimal DNA replication. Nucleic Acids Res 2004; 32:6218-25. [PMID: 15576348 PMCID: PMC535662 DOI: 10.1093/nar/gkh944] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Two cellular transcription factors, nuclear factor I (NFI) and octamer binding protein (Oct-1), bind simultaneously to their recognition sequences in the Ad5 origin of replication thereby enhancing initiation. Using scanning force microscopy we have previously shown that NFI induces a 60 degrees bend in the origin DNA. Here we demonstrate that Oct-1 induces a 42 degrees bend in the origin DNA. Simultaneous binding of NFI and Oct-1 induces an 82 degrees collective bend suggesting that both bends are oriented towards each other. In functional replication assays we further demonstrate that this extensive DNA bending leads to a synergistic enhancement of DNA replication. We propose that collective DNA bending induced by NFI and Oct-1 facilitates the optimal assembly of the preinitiation complex and plays an important role in the stimulatory mechanism of NFI and Oct-1 in replication.
Collapse
Affiliation(s)
- Monika E Mysiak
- Department of Physiological Chemistry, University Medical Centre Utrecht and Centre for Biomedical Genetics, Universiteitsweg 100, 3584 CG Utrecht, The Netherlands
| | | | | | | |
Collapse
|
8
|
Muñoz-Espín D, Mateu MG, Villar L, Marina A, Salas M, Meijer WJJ. Phage phi29 DNA replication organizer membrane protein p16.7 contains a coiled coil and a dimeric, homeodomain-related, functional domain. J Biol Chem 2004; 279:50437-45. [PMID: 15371435 DOI: 10.1074/jbc.m403297200] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The Bacillus subtilis phage varphi29-encoded membrane protein p16.7 is one of the few proteins known to be involved in prokaryotic membrane-associated DNA replication. Protein p16.7 contains an N-terminal transmembrane domain responsible for membrane localization. A soluble variant lacking the N-terminal membrane anchor, p16.7A, forms dimers in solution, binds to DNA, and has affinity for the varphi29 terminal protein. Here we show that the soluble N-terminal half of p16.7A can form a dimeric coiled coil. However, a second domain, located in the C-terminal half of the protein, has been characterized as being the main domain responsible for p16.7 dimerization. This 70-residue C-terminal domain, named p16.7C, also constitutes the functional part of the protein as it binds to DNA and terminal protein. Sequence alignments, secondary structure predictions, and spectroscopic analyses suggest that p16.7C is evolutionarily related to DNA binding homeodomains, present in many eukaryotic transcriptional regulator proteins. Based on the results, a structural model of p16.7 is presented.
Collapse
Affiliation(s)
- Daniel Muñoz-Espín
- Instituto de Biología Molecular "Eladio Viñuela", Centro de Biología Molecular "Severo Ochoa", Universidad Autónoma, Canto Blanco, 28049 Madrid, Spain
| | | | | | | | | | | |
Collapse
|
9
|
Mysiak ME, Holthuizen PE, van der Vliet PC. The adenovirus priming protein pTP contributes to the kinetics of initiation of DNA replication. Nucleic Acids Res 2004; 32:3913-20. [PMID: 15273278 PMCID: PMC506811 DOI: 10.1093/nar/gkh726] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Adenovirus (Ad) precursor terminal protein (pTP) in a complex with Ad DNA polymerase (pol) serves as a primer for Ad DNA replication. During initiation, pol covalently couples the first dCTP with Ser-580 of pTP. By using an in vitro reconstituted replication system comprised of purified proteins, we demonstrate that the conserved Asp-578 and Asp-582 residues of pTP, located close to Ser-580, are important for the initiation activity of the pTP/pol complex. In particular, the negative charge of Asp-578 is essential for this process. The introduced pTP mutations do not alter the binding capacity to DNA or polymerase, suggesting that the priming mechanism is affected. The Asp-578 or Asp-582 mutations increase the Km for dCTP incorporation, and higher dCTP concentrations or Mn2+ replacing Mg2+ partially relieve the initiation defect. Moreover, the kcat/Km values are reduced as a consequence of the pTP mutations. These observations demonstrate that pTP influences the catalytic activity of pol in initiation. Since both Asp residues are situated close to the pol active site during initiation, they may contribute to correct positioning of the OH group in Ser-580. Our results indicate that specific amino acids of the protein primer influence the ability of Ad5 DNA polymerase to initiate DNA replication.
Collapse
Affiliation(s)
- Monika E Mysiak
- Department of Physiological Chemistry, University Medical Centre Utrecht, Universiteitsweg 100, 3584 CG Utrecht, The Netherlands
| | | | | |
Collapse
|
10
|
Mysiak ME, Bleijenberg MH, Wyman C, Holthuizen PE, van der Vliet PC. Bending of adenovirus origin DNA by nuclear factor I as shown by scanning force microscopy is required for optimal DNA replication. J Virol 2004; 78:1928-35. [PMID: 14747557 PMCID: PMC369512 DOI: 10.1128/jvi.78.4.1928-1935.2004] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Nuclear factor I (NFI) is a transcription factor that binds to the adenovirus type 5 (Ad5) origin of replication and recruits the adenovirus DNA polymerase, thereby stimulating initiation of DNA replication in vitro. Using scanning force microscopy, we demonstrate that NFI induces a 60 degrees bend upon binding to the origin. The A/T-rich region preceding the core recognition sequence of NFI influences the DNA bend angle, since substitution of A/T base pairs by G/C base pairs severely decreases bending. Mutations in the A/T-rich region do not affect binding of NFI to DNA. However, mutations that reduce the protein-induced bend lead to a loss of NFI-stimulated replication, indicating that DNA bending is functionally important. In contrast, basal initiation or DNA binding of the polymerase is not impaired by these origin mutations. We conclude that binding of NFI to the Ad5 origin causes structural changes in DNA that are essential for the stimulatory function of NFI in replication. We propose that NFI-induced origin bending facilitates the assembly of a functional initiation complex.
Collapse
Affiliation(s)
- Monika E Mysiak
- Department of Physiological Chemistry, University Medical Center Utrecht, and Centre for Biomedical Genetics, 3584 CG Utrecht, The Netherlands
| | | | | | | | | |
Collapse
|
11
|
Stracker TH, Cassell GD, Ward P, Loo YM, van Breukelen B, Carrington-Lawrence SD, Hamatake RK, van der Vliet PC, Weller SK, Melendy T, Weitzman MD. The Rep protein of adeno-associated virus type 2 interacts with single-stranded DNA-binding proteins that enhance viral replication. J Virol 2004; 78:441-53. [PMID: 14671124 PMCID: PMC303412 DOI: 10.1128/jvi.78.1.441-453.2004] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Adeno-associated virus (AAV) type 2 is a human parvovirus whose replication is dependent upon cellular proteins as well as functions supplied by helper viruses. The minimal herpes simplex virus type 1 (HSV-1) proteins that support AAV replication in cell culture are the helicase-primase complex of UL5, UL8, and UL52, together with the UL29 gene product ICP8. We show that AAV and HSV-1 replication proteins colocalize at discrete intranuclear sites. Transfections with mutant genes demonstrate that enzymatic functions of the helicase-primase are not essential. The ICP8 protein alone enhances AAV replication in an in vitro assay. We also show localization of the cellular replication protein A (RPA) at AAV centers under a variety of conditions that support replication. In vitro assays demonstrate that the AAV Rep68 and Rep78 proteins interact with the single-stranded DNA-binding proteins (ssDBPs) of Ad (Ad-DBP), HSV-1 (ICP8), and the cell (RPA) and that these proteins enhance binding and nicking of Rep proteins at the origin. These results highlight the importance of intranuclear localization and suggest that Rep interaction with multiple ssDBPs allows AAV to replicate under a diverse set of conditions.
Collapse
Affiliation(s)
- Travis H Stracker
- Laboratory of Genetics, The Salk Institute for Biological Studies, La Jolla, California 92037, USA
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
12
|
Abstract
Replication of the adenovirus genome is catalysed by adenovirus DNA polymerase in which the adenovirus preterminal protein acts as a protein primer. DNA polymerase and preterminal protein form a heterodimer which, in the presence of the cellular transcription factors NFI/CTFI and NFIII/Oct-1, binds to the origin of DNA replication. DNA replication is initiated by DNA polymerase mediated transfer of dCMP onto preterminal protein. Further DNA synthesis is catalysed by DNA polymerase in a strand displacement mechanism which also requires adenovirus DNA binding protein. Here, we discuss the role of individual proteins in this process as revealed by biochemical analysis, mutagenesis and molecular modelling.
Collapse
Affiliation(s)
- H Liu
- Centre for Biomolecular Science, Biomolecular Science Building, The University of St. Andrews, North Haugh, St. Andrews, KY16 9ST, UK
| | | | | |
Collapse
|
13
|
de Jong RN, Meijer LAT, van der Vliet PC. DNA binding properties of the adenovirus DNA replication priming protein pTP. Nucleic Acids Res 2003; 31:3274-86. [PMID: 12799455 PMCID: PMC162239 DOI: 10.1093/nar/gkg405] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The precursor terminal protein pTP is the primer for the initiation of adenovirus (Ad) DNA replication and forms a heterodimer with Ad DNA polymerase (pol). Pol can couple dCTP to pTP directed by the fourth nucleotide of the viral genome template strand in the absence of other replication proteins, which suggests that pTP/pol binding destabilizes the origin or stabilizes an unwound state. We analyzed the contribution of pTP to pTP/pol origin binding using various DNA oligonucleotides. We show that two pTP molecules bind cooperatively to short DNA duplexes, while longer DNA fragments are bound by single pTP molecules as well. Cooperative binding to short duplexes is DNA sequence independent and most likely mediated by protein/protein contacts. Furthermore, we observed that pTP binds single-stranded (ss)DNA with a minimal length of approximately 35 nt and that random ssDNA competed 25-fold more efficiently than random duplex DNA for origin binding by pTP. Remarkably, short DNA fragments with two opposing single strands supported monomeric pTP binding. pTP did not stimulate, but inhibited strand displacement by the Ad DNA binding and unwinding protein DBP. These observations suggest a mechanism in which the ssDNA affinity of pTP stabilizes Ad pol on partially unwound origin DNA.
Collapse
Affiliation(s)
- R N de Jong
- Department of Physiological Chemistry, University Medical Center Utrecht and Center for Biomedical Genetics, Universiteitsweg 100, 3584 CG Utrecht, The Netherlands
| | | | | |
Collapse
|
14
|
Wysocka J, Herr W. The herpes simplex virus VP16-induced complex: the makings of a regulatory switch. Trends Biochem Sci 2003; 28:294-304. [PMID: 12826401 DOI: 10.1016/s0968-0004(03)00088-4] [Citation(s) in RCA: 226] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
When herpes simplex virus (HSV) infects human cells, it is able to enter two modes of infection: lytic and latent. A key activator of lytic infection is a virion protein called VP16, which, upon infection of a permissive cell, forms a transcriptional regulatory complex with two cellular proteins - the POU-domain transcription factor Oct-1 and the cell-proliferation factor HCF-1 - to activate transcription of the first set of expressed viral genes. This regulatory complex, called the VP16-induced complex, reveals mechanisms of combinatorial control of transcription. The activities of Oct-1 and HCF-1 - two important regulators of cellular gene expression and proliferation - illuminate strategies by which HSV might coexist with its host.
Collapse
|
15
|
van Breukelen B, Brenkman AB, Holthuizen PE, van der Vliet PC. Adenovirus type 5 DNA binding protein stimulates binding of DNA polymerase to the replication origin. J Virol 2003; 77:915-22. [PMID: 12502807 PMCID: PMC140850 DOI: 10.1128/jvi.77.2.915-922.2003] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The adenovirus (Ad) DNA-binding protein (DBP) is essential for the elongation phase of Ad DNA replication by unwinding the template in an ATP-independent fashion, employing its capacity to form multimers. DBP also enhances the rate of initiation, with the highest levels obtained at low concentrations of Ad DNA polymerase (Pol). Here, we show that stimulation of initiation depends on the template conformation. Maximal stimulation, up to 15-fold, is observed on double-stranded or viral TP-containing origins. The stimulation is reduced on partially single-stranded origins and DBP does not enhance initiation any more once the origin is completely unwound. This suggests a role for DBP in origin unwinding that is comparable to its unwinding capacity during elongation. However, mutant DBP proteins defective in unwinding and elongation can still enhance initiation on ds templates. DBP also stimulates the binding of nuclear factor I (NFI) to the origin and lowers the K(m) for coupling of the first nucleotide to the precursor terminal protein by Pol. Mobility shift experiments reveal that DBP stimulates the binding of Pol on double-stranded origin and nonorigin DNA but not on single-stranded DNA. This effect is specific for DBP and is also seen with other DNA Pols. Our results suggest that, rather than by origin unwinding, DBP enhances initiation by modulating the origin conformation such that DNA Pol can bind more efficiently.
Collapse
Affiliation(s)
- Bas van Breukelen
- Department of Physiological Chemistry and Centre for Biomedical Genetics, University Medical Center Utrecht, The Netherlands
| | | | | | | |
Collapse
|