151
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Abstract
The goal of interaction proteomics that studies the protein-protein interactions of all expressed proteins is to understand biological processes that are strictly regulated by these interactions. The availability of entire genome sequences of many organisms and high-throughput analysis tools has led scientists to study the entire proteome (Pandey and Mann, 2000). There are various high-throughput methods for detecting protein interactions such as yeast two-hybrid approach and mass spectrometry to produce vast amounts of data that can be utilized to decipher protein functions in complicated biological networks. In this review, we discuss recent developments in analytical methods for large-scale protein interactions and the future direction of interaction proteomics.
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Affiliation(s)
- Sayeon Cho
- Laboratory of Proteome Analysis, Korea Research Institute of Bioscience and Biotechnology, P.O. Box 115, Yusong, Daejeon 305-600, South Korea.
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152
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Soares HD, Williams SA, Snyder PJ, Gao F, Stiger T, Rohlff C, Herath A, Sunderland T, Putnam K, White WF. Proteomic Approaches in Drug Discovery and Development. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2004; 61:97-126. [PMID: 15482813 DOI: 10.1016/s0074-7742(04)61005-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/08/2023]
Affiliation(s)
- Holly D Soares
- Pfizer Global Research and Development, Groton, CT 06340, USA
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153
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Torrens F. Table of Periodic Properties of Fullerenes Based on Structural Parameters. ACTA ACUST UNITED AC 2003; 44:60-7. [PMID: 14741011 DOI: 10.1021/ci030029x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The periodic table (PT) of the elements suggests that hydrogen could be the origin of everything else. The construction principle is an evolutionary process that is formally similar to those of Darwin and Oparin. The Kekulé structure count and permanence of the adjacency matrix of fullerenes are related to structural parameters involving the presence of contiguous pentagons p, q and r. Let p be the number of edges common to two pentagons, q the number of vertices common to three pentagons, and r the number of pairs of nonadjacent pentagon edges shared between two other pentagons. Principal component analysis (PCA) of the structural parameters and cluster analysis (CA) of the fullerenes permit classifying them and agree. A PT of the fullerenes is built based on the structural parameters, PCA and CA. The periodic law does not have the rank of the laws of physics. (1) The properties of the fullerenes are not repeated; only, and perhaps, their chemical character. (2) The order relationships are repeated, although with exceptions. The proposed statement is the following: The relationships that any fullerene p has with its neighbor p + 1 are approximately repeated for each period.
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Affiliation(s)
- Francisco Torrens
- Institut Universitari de Ciència Molecular, Universitat de València, Dr Moliner 50, E-46100 Burjassot, València, Spain
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154
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Brun C, Chevenet F, Martin D, Wojcik J, Guénoche A, Jacq B. Functional classification of proteins for the prediction of cellular function from a protein-protein interaction network. Genome Biol 2003; 5:R6. [PMID: 14709178 PMCID: PMC395738 DOI: 10.1186/gb-2003-5-1-r6] [Citation(s) in RCA: 220] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2003] [Revised: 10/06/2003] [Accepted: 11/14/2003] [Indexed: 11/10/2022] Open
Abstract
We here describe PRODISTIN, a new computational method allowing the functional clustering of proteins on the basis of protein-protein interaction data. This method, assessed biologically and statistically, enabled us to classify 11% of the Saccharomyces cerevisiae proteome into several groups, the majority of which contained proteins involved in the same biological process(es), and to predict a cellular function for many otherwise uncharacterized proteins.
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Affiliation(s)
- Christine Brun
- Laboratoire de Génétique et Physiologie du Développement, CNRS UMR6545, Parc Scientifique et Technologique de Luminy, Case 907, 13288 Marseille Cedex 9, France
| | - François Chevenet
- Centre d'Etude sur le Polymorphisme des Micro-organismes, CNRS/IRD UMR 9926, 911 avenue Agropolis, BP 6450, 34394 Montpellier Cedex 5, France
| | - David Martin
- Laboratoire de Génétique et Physiologie du Développement, CNRS UMR6545, Parc Scientifique et Technologique de Luminy, Case 907, 13288 Marseille Cedex 9, France
| | - Jérôme Wojcik
- Hybrigenics SA, 3/5 impasse Reille, 75014 Paris, France
| | - Alain Guénoche
- Institut de Mathématiques de Luminy, CNRS UPR9016, Parc Scientifique et Technologique de Luminy, Case 907, 13288 Marseille Cedex 9, France
| | - Bernard Jacq
- Laboratoire de Génétique et Physiologie du Développement, CNRS UMR6545, Parc Scientifique et Technologique de Luminy, Case 907, 13288 Marseille Cedex 9, France
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155
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Zhong J, Zhang H, Stanyon CA, Tromp G, Finley RL. A strategy for constructing large protein interaction maps using the yeast two-hybrid system: regulated expression arrays and two-phase mating. Genome Res 2003; 13:2691-9. [PMID: 14613974 PMCID: PMC403811 DOI: 10.1101/gr.1134603] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Maps representing the binary interactions among proteins have become valuable tools for understanding how proteins work together to mediate biological processes. One of the most effective methods for detecting biologically important protein interactions has been the yeast two-hybrid system. Here we present an efficient two-hybrid strategy to facilitate construction of protein interaction maps on a genome-wide scale. The strategy begins with two arrays of yeast expressing known proteins fused to either a DNA binding domain (BD), or a transcription activation domain (AD). The fusion proteins are conditionally expressed using regulated promoters that can be repressed during construction and amplification of the yeast arrays. Interaction assays are conducted in two phases. In the first phase, small pools of AD strains are mated with the array of BD strains. In the second phase, individual BD strains are mated with appropriate subsets of the AD array corresponding to positive pools in the first phase. This strategy has several advantages over previously described approaches, including the ability to detect interactions with proteins that inhibit yeast growth or that activate transcription as BD fusions. Moreover, by minimizing the number of mating operations and sequencing reactions needed to test large sets of binary interactions, this strategy is more efficient than either matrix or library screening approaches. We also present a three-dimensional pooling scheme to further increase the efficiency of large-scale two-hybrid analyses.
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Affiliation(s)
- Jinhui Zhong
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, Michigan 48201, USA
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156
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Bolser D, Dafas P, Harrington R, Park J, Schroeder M. Visualisation and graph-theoretic analysis of a large-scale protein structural interactome. BMC Bioinformatics 2003; 4:45. [PMID: 14531933 PMCID: PMC272926 DOI: 10.1186/1471-2105-4-45] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2003] [Accepted: 10/08/2003] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Large-scale protein interaction maps provide a new, global perspective with which to analyse protein function. PSIMAP, the Protein Structural Interactome Map, is a database of all the structurally observed interactions between superfamilies of protein domains with known three-dimensional structure in the PDB. PSIMAP incorporates both functional and evolutionary information into a single network. RESULTS We present a global analysis of PSIMAP using several distinct network measures relating to centrality, interactivity, fault-tolerance, and taxonomic diversity. We found the following results: Centrality: we show that the center and barycenter of PSIMAP do not coincide, and that the superfamilies forming the barycenter relate to very general functions, while those constituting the center relate to enzymatic activity. Interactivity: we identify the P-loop and immunoglobulin superfamilies as the most highly interactive. We successfully use connectivity and cluster index, which characterise the connectivity of a superfamily's neighbourhood, to discover superfamilies of complex I and II. This is particularly significant as the structure of complex I is not yet solved. Taxonomic diversity: we found that highly interactive superfamilies are in general taxonomically very diverse and are thus amongst the oldest. Fault-tolerance: we found that the network is very robust as for the majority of superfamilies removal from the network will not break up the network. CONCLUSIONS Overall, we can single out the P-loop containing nucleotide triphosphate hydrolases superfamily as it is the most highly connected and has the highest taxonomic diversity. In addition, this superfamily has the highest interaction rank, is the barycenter of the network (it has the shortest average path to every other superfamily in the network), and is an articulation vertex, whose removal will disconnect the network. More generally, we conclude that the graph-theoretic and taxonomic analysis of PSIMAP is an important step towards the understanding of protein function and could be an important tool for tracing the evolution of life at the molecular level.
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Affiliation(s)
- Dan Bolser
- Dunn Human Nutrition Unit, Medical Research Council, Cambridge CB2 2XY, UK
| | - Panos Dafas
- Department of Computing, City University, London EC1V 0HB, UK
| | - Richard Harrington
- Dunn Human Nutrition Unit, Medical Research Council, Cambridge CB2 2XY, UK
| | - Jong Park
- Dunn Human Nutrition Unit, Medical Research Council, Cambridge CB2 2XY, UK
- Department of BioSystems, Korea Advanced Institute of Science and Technology, Korea
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157
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Abstract
Vaccinia virus replication takes place in the cytoplasm of the host cell. The nearly 200 kbp genome owes part of its complexity to encoding most of the proteins involved in genome and mRNA synthesis. The multisubunit vaccinia virus RNA polymerase requires a separate set of virus-encoded proteins for the transcription of the early, intermediate and late classes of genes. Cell fractionation studies have provided evidence for a role for host cell proteins in the initiation and termination of vaccinia virus intermediate and late gene transcription. Vaccinia virus resembles nuclear DNA viruses in the integration of viral and host proteins for viral mRNA synthesis, yet is markedly less reliant on host proteins than its nuclear counterparts.
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Affiliation(s)
- Steven S Broyles
- Department of Biochemistry, Purdue University, West Lafayette, IN 47907-1153, USA
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158
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Scaramozzino N, Sanz G, Crance JM, Saparbaev M, Drillien R, Laval J, Kavli B, Garin D. Characterisation of the substrate specificity of homogeneous vaccinia virus uracil-DNA glycosylase. Nucleic Acids Res 2003; 31:4950-7. [PMID: 12907738 PMCID: PMC169932 DOI: 10.1093/nar/gkg672] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The decision to stop smallpox vaccination and the loss of specific immunity in a large proportion of the population could jeopardise world health due to the possibility of a natural or provoked re-emergence of smallpox. Therefore, it is mandatory to improve the current capability to prevent or treat such infections. The DNA repair protein uracil-DNA glycosylase (UNG) is one of the viral enzymes important for poxvirus pathogenesis. Consequently, the inhibition of UNG could be a rational strategy for the treatment of infections with poxviruses. In order to develop inhibitor assays for UNG, as a first step, we have characterised the recombinant vaccinia virus UNG (vUNG) and compared it with the human nuclear form (hUNG2) and catalytic fragment (hUNG) UNG. In contrast to hUNG2, vUNG is strongly inhibited in the presence of 7.5 mM MgCl(2). We have shown that highly purified vUNG is not inhibited by a specific uracil-DNA glycosylase inhibitor. Interestingly, both viral and human enzymes preferentially excise uracil when it is opposite to cytosine. The present study provides the basis for the design of specific inhibitors for vUNG.
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Affiliation(s)
- Natale Scaramozzino
- Laboratoire de Virologie, Centre de Recherches du Service de Santé des Armées (CRSSA) Emile Pardé, Grenoble, France
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159
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Upton C, Slack S, Hunter AL, Ehlers A, Roper RL. Poxvirus orthologous clusters: toward defining the minimum essential poxvirus genome. J Virol 2003; 77:7590-600. [PMID: 12805459 PMCID: PMC164831 DOI: 10.1128/jvi.77.13.7590-7600.2003] [Citation(s) in RCA: 209] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2002] [Accepted: 03/26/2003] [Indexed: 11/20/2022] Open
Abstract
Increasingly complex bioinformatic analysis is necessitated by the plethora of sequence information currently available. A total of 21 poxvirus genomes have now been completely sequenced and annotated, and many more genomes will be available in the next few years. First, we describe the creation of a database of continuously corrected and updated genome sequences and an easy-to-use and extremely powerful suite of software tools for the analysis of genomes, genes, and proteins. These tools are available free to all researchers and, in most cases, alleviate the need for using multiple Internet sites for analysis. Further, we describe the use of these programs to identify conserved families of genes (poxvirus orthologous clusters) and have named the software suite POCs, which is available at www.poxvirus.org. Using POCs, we have identified a set of 49 absolutely conserved gene families-those which are conserved between the highly diverged families of insect-infecting entomopoxviruses and vertebrate-infecting chordopoxviruses. An additional set of 41 gene families conserved in chordopoxviruses was also identified. Thus, 90 genes are completely conserved in chordopoxviruses and comprise the minimum essential genome, and these will make excellent drug, antibody, vaccine, and detection targets. Finally, we describe the use of these tools to identify necessary annotation and sequencing updates in poxvirus genomes. For example, using POCs, we identified 19 genes that were widely conserved in poxviruses but missing from the vaccinia virus strain Tian Tan 1998 GenBank file. We have reannotated and resequenced fragments of this genome and verified that these genes are conserved in Tian Tan. The results for poxvirus genes and genomes are discussed in light of evolutionary processes.
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Affiliation(s)
- Chris Upton
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada.
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160
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161
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Abstract
The topology of the proteome map revealed by recent large-scale hybridization methods has shown that the distribution of protein-protein interactions is highly heterogeneous, with many proteins having few edges while a few of them are heavily connected. This particular topology is shared by other cellular networks, such as metabolic pathways, and it has been suggested to be responsible for the high mutational homeostasis displayed by the genome of some organisms. In this paper we explore a recent model of proteome evolution that has been shown to reproduce many of the features displayed by its real counterparts. The model is based on gene duplication plus re-wiring of the newly created genes. The statistical features displayed by the proteome of well-known organisms are reproduced and suggest that the overall topology of the protein maps naturally emerges from the two leading mechanisms considered by the model.
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Affiliation(s)
- Romualdo Pastor-Satorras
- Dept. de Fisica, FEN, Universitat Politècnica de Catalunya, Campus Nord B4, 08034 Barcelona, Spain
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162
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Ward BM, Weisberg AS, Moss B. Mapping and functional analysis of interaction sites within the cytoplasmic domains of the vaccinia virus A33R and A36R envelope proteins. J Virol 2003; 77:4113-26. [PMID: 12634370 PMCID: PMC150634 DOI: 10.1128/jvi.77.7.4113-4126.2003] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Incorporation of the vaccinia virus A36R protein into the outer membrane of intracellular enveloped virions (IEV) is dependent on expression of the A33R protein. Possible interactions of the 200-amino-acid cytoplasmic domain of the A36R protein with itself or with the cytoplasmic domain of the A33R, A34R, B5R, or F12L IEV membrane protein was investigated by using the yeast two-hybrid system. A strong interaction was detected only between the cytoplasmic domains of the A36R and A33R proteins. Upon further analyses, the interaction site was mapped to residues 91 to 111 of the A36R protein. To investigate the role of the A36R:A33R interaction during viral infection, five recombinant vaccinia viruses containing B5R-GFP as a marker were constructed. Four had the full-length A36R gene replaced with various-length C-terminal truncations of A36R, of which two contained residues 91 to 111 and two were missing this region. The fifth recombinant virus had an A33R gene with most of the 40-amino-acid cytoplasmic tail deleted. Residues 91 to 111 of A36R and the cytoplasmic tail of A33R were required for a strong interaction between the two proteins during viral infection and for maximal amounts of A36R protein on IEV. Mutants lacking these regions of A33R or A36R formed IEV that exhibited only short sporadic intracellular movement, displayed no actin tails, and formed small plaques on cell monolayers equivalent to those of an A36R deletion mutant and smaller than those formed by point mutations that specifically abrogate actin tail formation. The A33R interaction site of the A36R protein is highly conserved among orthopoxviruses and may overlap binding sites for cellular proteins needed for microtubular movement and actin tail formation.
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Affiliation(s)
- Brian M Ward
- Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892-0445, USA
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163
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Abstract
The availability of complete, annotated genome sequences for a variety of eukaryotic organisms has paved the way for a paradigm shift in biomedical research from the 'one gene-one hypothesis' approach to more global, systematic strategies that analyse genes or proteins on a genome- and proteome-wide scale. One daunting task in the post-genome era is to determine how the complement of expressed cellular proteins - the proteome - is organised into functional, higher-order networks, by mapping all constitutive and dynamic protein-protein interactions. Traditionally, reductionist approaches have typically focused on a few, selected gene products and their interactions in a particular physiological context. In contrast, more holistic strategies aim at understanding complex biological systems, for example global protein-protein interaction networks on a cellular or organismal level. Several large-scale proteomics technologies have been developed to generate comprehensive, cellular protein-protein interaction maps.
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Affiliation(s)
- Gerard Drewes
- Cellzome AG, Meyerhofstrasse 1, 69117, Heidelberg, Germany.
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164
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Abstract
Proteomics is the systematic study of the many and diverse properties of proteins in a parallel manner with the aim of providing detailed descriptions of the structure, function and control of biological systems in health and disease. Advances in methods and technologies have catalyzed an expansion of the scope of biological studies from the reductionist biochemical analysis of single proteins to proteome-wide measurements. Proteomics and other complementary analysis methods are essential components of the emerging 'systems biology' approach that seeks to comprehensively describe biological systems through integration of diverse types of data and, in the future, to ultimately allow computational simulations of complex biological systems.
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Affiliation(s)
- Scott D Patterson
- Celera Genomics Corporation, 45 West Gude Drive, Rockville, Maryland 20850, USA.
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165
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Abstract
Protein complexes may well be the most relevant molecular units of cellular function. The activities of protein complexes have to be regulated both in time and space to integrate within the overall cell programs. The cell can be compared to a factory orchestrating individual assembly lines into integrated networks fulfilling particular and superimposed tasks. Recent proteome-wide studies provide insight into the properties of cellular protein complexes, their modular nature, their interaction with other complexes and the resulting preliminary organization chart of the proteome.
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166
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De Silva FS, Moss B. Vaccinia virus uracil DNA glycosylase has an essential role in DNA synthesis that is independent of its glycosylase activity: catalytic site mutations reduce virulence but not virus replication in cultured cells. J Virol 2003; 77:159-66. [PMID: 12477821 PMCID: PMC140647 DOI: 10.1128/jvi.77.1.159-166.2003] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Previous findings that the vaccinia virus uracil DNA glycosylase is required for virus DNA replication, coupled with an inability to isolate a mutant with an active site substitution in the glycosylase gene, were surprising, as such enzymes function in DNA repair and bacterial, yeast, and mammalian null mutants are viable. To further study the role of the viral protein, we constructed recombinant vaccinia viruses with single or double mutations (D68N and H181L) in the uracil DNA glycosylase conserved catalytic site by using a complementing cell line that constitutively expresses the viral enzyme. Although these mutations abolished uracil DNA glycosylase activity, they did not prevent viral DNA replication or propagation on a variety of noncomplementing cell lines or human primary skin fibroblasts. In contrast, replication of a uracil DNA glycosylase deletion mutant occurred only in the complementing cell line. Therefore, the uracil DNA glycosylase has an essential role in DNA replication that is independent of its glycosylase activity. Nevertheless, the conservation of the catalytic site in all poxvirus orthologs suggested an important role in vivo. This idea was confirmed by the decreased virulence of catalytic-site mutants when administered by the intranasal route to mice.
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Affiliation(s)
- Frank S De Silva
- Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892-0445, USA
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167
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Schächter V. Construction and prediction of protein-protein interaction maps. ERNST SCHERING RESEARCH FOUNDATION WORKSHOP 2002:191-220. [PMID: 12061003 DOI: 10.1007/978-3-662-04747-7_10] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/25/2023]
Affiliation(s)
- V Schächter
- VP Science and Technology Hybrigenics SA, 180 Avenue Daumesnil, 75012 Paris, France.
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168
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Ishii K, Moss B. Mapping interaction sites of the A20R protein component of the vaccinia virus DNA replication complex. Virology 2002; 303:232-9. [PMID: 12490386 DOI: 10.1006/viro.2002.1721] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The vaccinia virus A20R protein is required for DNA replication, is associated with the processive form of the viral DNA polymerase, and directly interacts with the viral proteins encoded by the D4R, D5R, and H5R open reading frames as determined by a genome-wide yeast two-hybrid analysis. The purpose of the present study was to further analyze the latter protein-protein interactions. Association of an epitope-tagged A20R protein with an epitope-tagged D4R or H5R protein, expressed in vaccinia virus-infected cells, was demonstrated by binding the complex to one mAb followed by Western blotting with another. Interaction between the A20R and D5R proteins, which was weakest in the yeast two-hybrid analysis, could not be demonstrated by this method. A panel of N- and C-terminal truncated forms of the A20R protein was tested for interaction with the D4R, H5R, and D5R proteins using the yeast two-hybrid system. These studies revealed that nonoverlapping regions of A20R comprising amino acids 1 to 25, 26 to 76, and 201 to 251 were required for binding of D4R, H5R, and D5R, respectively. By contrast, no interaction of A20R with D4R could be detected after deletion of only 25 codons from either end of the latter open reading frame. A fusion protein containing either full-length A20R or only the N-terminal 25 amino acids of A20R was sufficient to capture the D4R protein, whereas the fusion protein containing A20R amino acids 26 to 426 was not, confirming the results of the yeast two-hybrid analysis. The distinct protein binding domains of the A20R protein may contribute to the assembly or stability of the multiprotein DNA replication complex.
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Affiliation(s)
- Koji Ishii
- Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892-0445, USA
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169
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Chiu WL, Chang W. Vaccinia virus J1R protein: a viral membrane protein that is essential for virion morphogenesis. J Virol 2002; 76:9575-87. [PMID: 12208937 PMCID: PMC136503 DOI: 10.1128/jvi.76.19.9575-9587.2002] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Vaccinia virus, a member of the poxvirus family, contains a conserved J1R open reading frame that encodes a late protein of 17.8 kDa. The 18-kDa J1R protein is associated mainly with the membrane fraction of intracellular mature virus particles. This study examines the biological function of J1R protein in the vaccinia virus life cycle. A recombinant vaccinia virus was constructed to conditionally express J1R protein in an isopropyl-beta-D-galactopyranoside (IPTG)-inducible manner. When J1R is not expressed during vaccinia virus infection, the virus titer is reduced approximately 100-fold. In contrast, J1R protein is not required for viral gene expression, as indicated by protein pulse-labeling. J1R protein is also not required for DNA processing, as the resolution of the concatemer junctions of replicated viral DNA was detected without IPTG. A deficiency of J1R protein caused a severe delay in the processing of p4a and p4b into mature core proteins 4a and 4b, indicating that J1R protein participates in virion morphogenesis. Infected cells grown in the absence of IPTG contained very few intracellular mature virions in the cytoplasm, and enlarged viroplasm structures accumulated with viral crescents attached at the periphery. Abundant intermediate membrane structures of abnormal shapes were observed, and many immature virions were either empty or partially filled, indicating that J1R protein is important for DNA packaging into immature virions. J1R protein also coimmunoprecipited with A45R protein in infected cells. In summary, these results indicate that vaccinia virus J1R is a membrane protein that is required for virus growth and plaque formation. J1R protein interacts with A45R protein and performs an important role during immature virion formation in cultured cells.
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Affiliation(s)
- Wen-Ling Chiu
- Graduate Institute of Life Science, National Defense Medical Center. Institute of Molecular Biology, Academia Sinica, Nankang, Taipei, Taiwan, Republic of China
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170
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Abstract
With the sequencing of many genomes now completed, biologists are faced with the challenge of deciphering the function and association of an immense number of predicted proteins. Comprehension of the networks of proteins and chemicals that comprise the cells and tissues of an organism, and the specific roles of proteins in these networks, will be a necessary next step to understanding cellular function in healthy and diseased states. In the past decade, the budding yeast Saccharomyces cerevisiae has emerged as an important tool for large-scale functional genomics analyses. This review describes the use of yeast cell-based assays in the post-genomic era, focusing on high-throughput functional genomics and drug discovery.
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Affiliation(s)
- Chandra L Tucker
- Dept of Genome Sciences, University of Washington, Box 357730, Seattle, WA 98195, USA.
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171
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Condit RC, Niles EG. Regulation of viral transcription elongation and termination during vaccinia virus infection. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1577:325-36. [PMID: 12213661 DOI: 10.1016/s0167-4781(02)00461-x] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Vaccinia virus provides a useful genetic and biochemical tool for studies of the basic mechanisms of eukaryotic transcription. Vaccinia genes are transcribed in three successive gene classes during infection, early, intermediate, and late. Vaccinia transcription is regulated primarily by virus gene products not only during initiation, but also during elongation and termination. The factors and mechanisms regulating early elongation and termination differ from those regulating intermediate and late gene expression. Control of transcription elongation and termination in vaccinia virus bears some similarity to the same process in other prokaryotic and eukaryotic systems, yet features some novel mechanisms as well.
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Affiliation(s)
- Richard C Condit
- Department of Molecular Genetics and Microbiology, P.O. Box 100266, University of Florida, Gainesville, FL 32610, USA.
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172
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Senkevich TG, White CL, Weisberg A, Granek JA, Wolffe EJ, Koonin EV, Moss B. Expression of the vaccinia virus A2.5L redox protein is required for virion morphogenesis. Virology 2002; 300:296-303. [PMID: 12350360 DOI: 10.1006/viro.2002.1608] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In this article we report the initial biochemical, genetic, and electron microscopic analysis of a previously uncharacterized, 8.9-kDa, predicted thiol-redox protein. The name A2.5L was assigned to the corresponding vaccinia virus gene, which is conserved in all sequenced poxviruses. Multiple alignment analysis and secondary structure prediction indicated that the A2.5L gene product is an all-alpha-helical protein with a conserved Cxx(x)C motif in the N-terminal alpha-helix. The DNA replication requirement and kinetics of A2.5L protein accumulation in virus-infected cells were typical of a late gene product, in agreement with the predicted promoter sequence. The A2.5L protein was a monomer under reducing conditions, but was mostly associated with the vaccinia virus E10R redox protein as a heterodimer under nonreducing conditions. The A2.5L protein was detected in virus particles at various stages of assembly, suggesting that it is an integral component of intracellular virions. An inducer-dependent A2.5L null mutant was constructed: in the absence of inducer, infectious virus formation was abolished and electron microscopy revealed an assembly block with an accumulation of crescent membranes and immature virions. This stage of assembly block was similar to that occurring when the E10R and G4L redox proteins were repressed, which is compatible with the involvement of E10R, A2.5L, and G4L in the same redox pathway.
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Affiliation(s)
- Tatiana G Senkevich
- Laboratory of viral Deseases, National Institute of Allergy and Infectious Desseases, Bethesda, Maryland 20892, USA
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173
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Karimova G, Ladant D, Ullmann A. Two-hybrid systems and their usage in infection biology. Int J Med Microbiol 2002; 292:17-25. [PMID: 12139424 DOI: 10.1078/1438-4221-00182] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Two-hybrid systems are powerful tools to study protein-protein interactions in biological systems. The role of protein-protein interactions involved in pathogenesis of bacterial and viral infections were defined by using yeast or bacterial two-hybrid screens. Examples are given to highlight the specificity of interactions in signaling pathways, in regulation, secretion and structure-function relationships of virulence factors and their cellular targets. Two-hybrid systems were also used to establish large-scale protein interaction maps of viral and bacterial pathogens, that might be useful to identify targets for new drugs or vaccines.
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Affiliation(s)
- Gouzel Karimova
- Unité de Biochimie Cellulaire, CNRS URA 2185, Institut Pasteur, Paris, France
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174
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Abstract
The availability of completed genome sequences of several eukaryotic and prokaryotic species has shifted the focus towards the identification and characterization of all gene products that are expressed in a given organism. In order to cope with the huge amounts of data that have been provided by large-scale sequencing projects, high-throughout methodologies also need to be applied in the emerging field of proteomics. In this review, we discuss methods that have been recently developed in order to characterize protein interactions and their functional relevance on a large scale. We then focus on those methodologies that are suitable for the identification and characterization of protein-protein interactions, namely the yeast two-hybrid system and related methods. Several recent studies have demonstrated the power of automated approaches involving the yeast two-hybrid system in building so-called "interaction networks", which hold the promise of identifying the entirety of all interactions that take place between proteins expressed in a certain cell type or organism. We compare the yeast two-hybrid system with several other screening methods that have been developed to investigate interactions between proteins that are not amenable to conventional yeast two-hybrid screenings, such as transcriptional activators and integral membrane proteins. The eventual adaptation of such methods to a high-throughput format and their use in combination with automated yeast two-hybrid screenings will help in elucidating protein-protein interactions on a scale that would have been unthinkable just a few years ago.
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175
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Abstract
Functional proteomics approaches aim to characterize comprehensively the function of gene products, and provide a first-level understanding of cellular mechanisms. Here, we review recent techniques for the construction and prediction of large-scale protein-interaction networks, with a particular emphasis on computational processing steps and comparative assessment of the reliability and completeness of the various approaches. We also discuss the use of protein-interaction network information in functional annotation and in the generation of higher-level biological hypotheses on pathways.
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176
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Tulman ER, Afonso CL, Lu Z, Zsak L, Sur JH, Sandybaev NT, Kerembekova UZ, Zaitsev VL, Kutish GF, Rock DL. The genomes of sheeppox and goatpox viruses. J Virol 2002; 76:6054-61. [PMID: 12021338 PMCID: PMC136203 DOI: 10.1128/jvi.76.12.6054-6061.2002] [Citation(s) in RCA: 240] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Sheeppox virus (SPPV) and goatpox virus (GTPV), members of the Capripoxvirus genus of the Poxviridae, are etiologic agents of important diseases of sheep and goats in northern and central Africa, southwest and central Asia, and the Indian subcontinent. Here we report the genomic sequence and comparative analysis of five SPPV and GTPV isolates, including three pathogenic field isolates and two attenuated vaccine viruses. SPPV and GTPV genomes are approximately 150 kbp and are strikingly similar to each other, exhibiting 96% nucleotide identity over their entire length. Wild-type genomes share at least 147 putative genes, including conserved poxvirus replicative and structural genes and genes likely involved in virulence and host range. SPPV and GTPV genomes are very similar to that of lumpy skin disease virus (LSDV), sharing 97% nucleotide identity. All SPPV and GTPV genes are present in LSDV. Notably in both SPPV and GTPV genomes, nine LSDV genes with likely virulence and host range functions are disrupted, including a gene unique to LSDV (LSDV132) and genes similar to those coding for interleukin-1 receptor, myxoma virus M003.2 and M004.1 genes (two copies each), and vaccinia virus F11L, N2L, and K7L genes. The absence of these genes in SPPV and GTPV suggests a significant role for them in the bovine host range. SPPV and GTPV genomes contain specific nucleotide differences, suggesting they are phylogenetically distinct. Relatively few genomic changes in SPPV and GTPV vaccine viruses account for viral attenuation, because they contain 71 and 7 genomic changes compared to their respective field strains. Notable genetic changes include mutation or disruption of genes with predicted functions involving virulence and host range, including two ankyrin repeat proteins in SPPV and three kelch-like proteins in GTPV. These comparative genomic data indicate the close genetic relationship among capripoxviruses, and they suggest that SPPV and GTPV are distinct and likely derived from an LSDV-like ancestor.
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Affiliation(s)
- E R Tulman
- Plum Island Animal Disease Center, Agricultural Research Service, U.S. Department of Agriculture, Greenport, New York 11944, USA
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177
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Senkevich TG, White CL, Koonin EV, Moss B. Complete pathway for protein disulfide bond formation encoded by poxviruses. Proc Natl Acad Sci U S A 2002; 99:6667-72. [PMID: 11983854 PMCID: PMC124460 DOI: 10.1073/pnas.062163799] [Citation(s) in RCA: 153] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
We show that three cytoplasmic thiol oxidoreductases encoded by vaccinia virus comprise a complete pathway for formation of disulfide bonds in intracellular virion membrane proteins. The pathway was defined by analyzing conditional lethal mutants and effects of cysteine to serine substitutions and by trapping disulfide-bonded heterodimer intermediates for each consecutive step. The upstream component, E10R, belongs to the ERV1/ALR family of FAD-containing sulfhydryl oxidases that use oxygen as the electron acceptor. The second component, A2.5L, is a small alpha-helical protein with a CxxxC motif that forms a stable disulfide-linked heterodimer with E10R and a transient disulfide-linked complex with the third component, G4L. The latter is a thioredoxin-like protein that directly oxidizes thiols of L1R, a structural component of the virion membrane with three stable disulfide bonds, and of the related protein F9L. These five proteins are conserved in all poxviruses, suggesting that the pathway is an ancestral mechanism for direct thiol-disulfide interchanges between proteins even in an unfavorable reducing environment.
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Affiliation(s)
- Tatiana G Senkevich
- Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
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178
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Kluczyk A, Siemion IZ, Szewczuk Z, Wieczorek Z. The immunosuppressive activity of peptide fragments of vaccinia virus C10L protein and a hypothesis on the role of this protein in the viral invasion. Peptides 2002; 23:823-34. [PMID: 12084512 DOI: 10.1016/s0196-9781(02)00006-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Our previous studies revealed that the 143-148 fragment of interleukin-1 receptor antagonist (IL-1 Ra) molecule with a Val-Thr-Lys-Phe-Tyr-Phe (VTKFYF) sequence inhibits the interleukin-1 (IL-1) interaction with its cellular receptor. The Val-Thr-Arg-Phe-Tyr-Phe (VTRFYF) sequence of the 322-327 fragment of the C-terminal domain of vaccinia virus protein related to the C10L vaccinia gene shows a very high homology to the 143-148 IL-1 Ra fragment, suggesting a similar inhibitory activity. To test this suggestion, we investigated the inhibitory activity of a series of synthetic peptides derived from 316 to 327 fragment of C10L on the interaction of IL-1 with its receptor. We also tested the peptides for their influence on the humoral and cellular immune response. The results indicate that biological activities of the C10L fragments are similar to those obtained for respective fragments of IL-1 Ra. The C-terminal domain of C10L protein can be easily folded into spatial structure similar to the crystallographic one of IL-1 Ra. Based on the crystallographic structure of IL-1 Ra, we constructed a 3-D model of the C10L protein. According to the model, the Val(322)-Asn(328) sequence is localized on the surface of the molecule and, therefore, it may be involved in the interactions with receptors. Our results indicate that the C10L viral protein can play an important role in vaccinia virus evasion of the host immune system. It may consist in the blockade of IL-1 receptors by the C10L protein, a homologue of the IL-1 Ra.
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Affiliation(s)
- Alicja Kluczyk
- Faculty of Chemistry, University of Wroclaw, 14 F. Joliot-Curie Street, Wroclaw, Poland
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179
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Zanzoni A, Montecchi-Palazzi L, Quondam M, Ausiello G, Helmer-Citterich M, Cesareni G. MINT: a Molecular INTeraction database. FEBS Lett 2002; 513:135-40. [PMID: 11911893 DOI: 10.1016/s0014-5793(01)03293-8] [Citation(s) in RCA: 585] [Impact Index Per Article: 25.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Protein interaction databases represent unique tools to store, in a computer readable form, the protein interaction information disseminated in the scientific literature. Well organized and easily accessible databases permit the easy retrieval and analysis of large interaction data sets. Here we present MINT, a database (http://cbm.bio.uniroma2.it/mint/index.html) designed to store data on functional interactions between proteins. Beyond cataloguing binary complexes, MINT was conceived to store other types of functional interactions, including enzymatic modifications of one of the partners. Release 1.0 of MINT focuses on experimentally verified protein-protein interactions. Both direct and indirect relationships are considered. Furthermore, MINT aims at being exhaustive in the description of the interaction and, whenever available, information about kinetic and binding constants and about the domains participating in the interaction is included in the entry. MINT consists of entries extracted from the scientific literature by expert curators assisted by 'MINT Assistant', a software that targets abstracts containing interaction information and presents them to the curator in a user-friendly format. The interaction data can be easily extracted and viewed graphically through 'MINT Viewer'. Presently MINT contains 4568 interactions, 782 of which are indirect or genetic interactions.
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Affiliation(s)
- Andreas Zanzoni
- Department of Biology, University of Rome Tor Vergata, Via della Ricerca Scientifica, 00133 Rome, Italy
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180
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Finley RL, Zhang H, Zhong J, Stanyon CA. Regulated expression of proteins in yeast using the MAL61-62 promoter and a mating scheme to increase dynamic range. Gene 2002; 285:49-57. [PMID: 12039031 DOI: 10.1016/s0378-1119(02)00420-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The ability to express heterologous genes in yeast has become indispensable for many biological research techniques. Expression systems that can be regulated are particularly useful because they allow an experimenter to control the timing and levels of gene expression. Despite their many advantages, however, surprisingly few conditional expression systems are available for yeast. Moreover, of those that have been described, many are not ideal either because they have high background expression levels, low induced levels, or because they require restrictive growth conditions. Here we describe a conditional expression system that takes advantage of the yeast MAL62 promoter (MAL62p), which can be controlled by adding maltose or glucose to the growth medium to induce or repress transcription, respectively. In addition, we use a mating scheme to dramatically increase the dynamic range of expression levels possible. We show that MAL62p background activity can be effectively eliminated by maintaining expression constructs in a mal(-) yeast strain. High-level expression can be induced in diploids formed by mating the mal(-) strain with a MAL(+) strain. A similar mating scheme may be useful for other conditional expression systems as well. Among other uses, this approach should aid high throughput yeast two-hybrid assays, which rely on maintaining large libraries of expression strains, which are eventually mated to conduct assays for protein interactions. We demonstrate a two-hybrid system in which MAL62p is used in conjunction with the yeast GAL1 promoter to independently regulate expression of both hybrid proteins, and to allow detection of interactions involving toxic proteins.
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Affiliation(s)
- Russell L Finley
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, 540 East Canfield Avenue, Detroit, MI 48201, USA.
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181
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Abstract
The two-hybrid system is a genetic method for detecting protein-protein interactions. The assay can be applied to random libraries or arrays of colonies that express defined pairs of proteins. Arrays enable the testing of all possible protein pairs for interactions in a systematic fashion. The array format makes a large number of individual assays comparable and thus greatly simplifies the identification of false positives. Two-hybrid arrays have been used to study interactions among the proteins of yeast, hepatitis C virus, vaccinia virus, Drosophila, Caenorhabditis elegans, mouse and other species, and have already identified thousands of interactions.
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Affiliation(s)
- Peter Uetz
- Institut fuür Toxikologie und Genetik, Forschungszentrum Karlsruhe, Postfach 3640, D-76021 Karlsruhe, Germany.
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182
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Afonso CL, Tulman ER, Lu Z, Zsak L, Osorio FA, Balinsky C, Kutish GF, Rock DL. The genome of swinepox virus. J Virol 2002; 76:783-90. [PMID: 11752168 PMCID: PMC136851 DOI: 10.1128/jvi.76.2.783-790.2002] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Swinepox virus (SWPV), the sole member of the Suipoxvirus genus of the Poxviridae, is the etiologic agent of a worldwide disease specific for swine. Here we report the genomic sequence of SWPV. The 146-kbp SWPV genome consists of a central coding region bounded by identical 3.7-kbp inverted terminal repeats and contains 150 putative genes. Comparison of SWPV with chordopoxviruses reveals 146 conserved genes encoding proteins involved in basic replicative functions, viral virulence, host range, and immune evasion. Notably, these include genes with similarity to genes for gamma interferon (IFN-gamma) receptor, IFN resistance protein, interleukin-18 binding protein, IFN-alpha/beta binding protein, extracellular enveloped virus host range protein, dUTPase, hydroxysteroid dehydrogenase, superoxide dismutase, serpin, herpesvirus major histocompatibility complex inhibitor, ectromelia virus macrophage host range protein, myxoma virus M011L, variola virus B22R, four ankyrin repeat proteins, three kelch-like proteins, five vaccinia virus (VV) A52R-like family proteins, and two G protein-coupled receptors. The most conserved genomic region is centrally located and corresponds to the VV region located between genes F9L and A38L. Within the terminal 13 kbp, colinearity is disrupted and multiple poxvirus gene homologues are absent or share a lower percentage of amino acid identity. Most of these differences involve genes and gene families with likely functions involving viral virulence and host range. Three open reading frames (SPV018, SPV019. and SPV020) are unique for SWPV. Phylogenetic analysis, genome organization, and amino acid identity indicate that SWPV is most closely related to the capripoxvirus lumpy skin disease virus, followed by the yatapoxvirus yaba-like disease virus and the leporipoxviruses. The gene complement of SWPV better defines Suipoxvirus within the Chordopoxvirinae subfamily and provides a basis for future genetic comparisons.
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Affiliation(s)
- C L Afonso
- Plum Island Animal Disease Center, Agricultural Research Service, U.S. Department of Agriculture, Greenport, New York 11944, USA.
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183
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Klemperer N, McDonald W, Boyle K, Unger B, Traktman P. The A20R protein is a stoichiometric component of the processive form of vaccinia virus DNA polymerase. J Virol 2001; 75:12298-307. [PMID: 11711620 PMCID: PMC116126 DOI: 10.1128/jvi.75.24.12298-12307.2001] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In vitro analysis of the catalytic DNA polymerase encoded by vaccinia virus has demonstrated that it is innately distributive, catalyzing the addition of <10 nucleotides per primer-template binding event in the presence of 8 mM MgCl(2) or 40 mM NaCl (W. F. McDonald and P. Traktman, J. Biol. Chem. 269:31190-31197, 1994). In contrast, cytoplasmic extracts isolated from vaccinia virus-infected cells contain a highly processive form of DNA polymerase, able to catalyze the replication of a 7-kb template per binding event under similar conditions. To study this holoenzyme, we were interested in purifying and characterizing the vaccinia virus processivity factor (VPF). Our previous studies indicated that VPF is expressed early after infection and has a native molecular mass of approximately 48 kDa (W. F. McDonald, N. Klemperer, and P. Traktman, Virology 234:168-175, 1997). Using these criteria, we established a six-step chromatographic purification procedure, in which a prominent approximately 45-kDa band was found to copurify with processive polymerase activity. This species was identified as the product of the A20 gene. By use of recombinant viruses that direct the overexpression of A20 and/or the DNA polymerase, we verified the physical interaction between the two proteins in coimmunoprecipitation experiments. We also demonstrated that simultaneous overexpression of A20 and the DNA polymerase leads to a specific and robust increase in levels of processive polymerase activity. Taken together, we conclude that the A20 gene encodes a component of the processive DNA polymerase complex. Genetic data that further support this conclusion are presented in the accompanying report, which documents that temperature-sensitive mutants with lesions in the A20 gene have a DNA(-) phenotype that correlates with a deficit in processive polymerase activity (A. Punjabi et al, J. Virol. 75:12308-12318, 2001).
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Affiliation(s)
- N Klemperer
- Department of Cell Biology and Anatomy, Weill Medical College of Cornell University, New York, New York 10021, USA
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184
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Matthews LR, Vaglio P, Reboul J, Ge H, Davis BP, Garrels J, Vincent S, Vidal M. Identification of potential interaction networks using sequence-based searches for conserved protein-protein interactions or "interologs". Genome Res 2001; 11:2120-6. [PMID: 11731503 PMCID: PMC311221 DOI: 10.1101/gr.205301] [Citation(s) in RCA: 369] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Protein interaction maps have provided insight into the relationships among the predicted proteins of model organisms for which a genome sequence is available. These maps have been useful in generating potential interaction networks, which have confirmed the existence of known complexes and pathways and have suggested the existence of new complexes and or crosstalk between previously unlinked pathways. However, the generation of such maps is costly and labor intensive. Here, we investigate the extent to which a protein interaction map generated in one species can be used to predict interactions in another species.
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Affiliation(s)
- L R Matthews
- Dana-Farber Cancer Institute and Department of Genetcis, Harvard Medical School, Boston, Massachusetts, USA
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185
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Punjabi A, Boyle K, DeMasi J, Grubisha O, Unger B, Khanna M, Traktman P. Clustered charge-to-alanine mutagenesis of the vaccinia virus A20 gene: temperature-sensitive mutants have a DNA-minus phenotype and are defective in the production of processive DNA polymerase activity. J Virol 2001; 75:12308-18. [PMID: 11711621 PMCID: PMC116127 DOI: 10.1128/jvi.75.24.12308-12318.2001] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Although the vaccinia virus DNA polymerase is inherently distributive, a highly processive form of the enzyme exists within the cytoplasm of infected cells (W. F. McDonald, N. Klemperer, and P. Traktman, Virology 234:168-175, 1997). In the accompanying report we outline the purification of the 49-kDa A20 protein as a stoichiometric component of the processive polymerase complex (N. Klemperer, W. McDonald, K. Boyle, B. Unger, and P. Traktman, J. Virol. 75:12298-12307, 2001). To complement this biochemical analysis, we undertook a genetic approach to the analysis of the structure and function of the A20 protein. Here we report the application of clustered charge-to-alanine mutagenesis of the A20 gene. Eight mutant viruses containing altered A20 alleles were isolated using this approach; two of these, tsA20-6 and tsA20-ER5, have tight temperature-sensitive phenotypes. At the nonpermissive temperature, neither virus forms macroscopic plaques and the yield of infectious virus is <1% of that obtained at the permissive temperature. Both viruses show a profound defect in the accumulation of viral DNA at the nonpermissive temperature, although both the A20 protein and DNA polymerase accumulate to wild-type levels. Cytoplasmic extracts prepared from cells infected with the tsA20 viruses show a defect in processive polymerase activity; they are unable to direct the formation of RFII product using a singly primed M13 template. In sum, these data indicate that the A20 protein plays an essential role in the viral life cycle and that viruses with A20 lesions exhibit a DNA(-) phenotype that is correlated with a loss in processive polymerase activity as assayed in vitro. The vaccinia virus A20 protein can, therefore, be considered a new member of the family of proteins (E9, B1, D4, and D5) with essential roles in vaccinia virus DNA replication.
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Affiliation(s)
- A Punjabi
- Department of Microbiology and Molecular Genetics, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA
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186
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Kellam P. Post-genomic virology: the impact of bioinformatics, microarrays and proteomics on investigating host and pathogen interactions. Rev Med Virol 2001; 11:313-29. [PMID: 11590669 DOI: 10.1002/rmv.328] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Post-genomic research encompasses many diverse aspects of modern science. These include the two broad subject areas of computational biology (bioinformatics) and functional genomics. Laboratory based functional genomics aims to measure and assess either the messenger RNA (mRNA) levels (transcriptome studies) or the protein content (proteome studies) of cells and tissues. All of these methods have been applied recently to the study of host and pathogen interactions for both bacteria and viruses. A basic overview of the technology is given in this review together with approaches to data analysis. The wealth of information produced from even these preliminary studies has shown the generalities, subtleties and specificities of host-pathogen interactions. Such research should ultimately result in new methods for diagnosing and treating infectious diseases.
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Affiliation(s)
- P Kellam
- Wohl Virion Centre, Department of Immunology and Molecular Pathology, Windeyer Institute of Medical Sciences, University College London, 46 Cleveland Street, London W1T 4JF, UK.
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187
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Sprinzak E, Margalit H. Correlated sequence-signatures as markers of protein-protein interaction. J Mol Biol 2001; 311:681-92. [PMID: 11518523 DOI: 10.1006/jmbi.2001.4920] [Citation(s) in RCA: 224] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
As protein-protein interaction is intrinsic to most cellular processes, the ability to predict which proteins in the cell interact can aid significantly in identifying the function of newly discovered proteins, and in understanding the molecular networks they participate in. Here we demonstrate that characteristic pairs of sequence-signatures can be learned from a database of experimentally determined interacting proteins, where one protein contains the one sequence-signature and its interacting partner contains the other sequence-signature. The sequence-signatures that recur in concert in various pairs of interacting proteins are termed correlated sequence-signatures, and it is proposed that they can be used for predicting putative pairs of interacting partners in the cell. We demonstrate the potential of this approach on a comprehensive database of experimentally determined pairs of interacting proteins in the yeast Saccharomyces cerevisiae. The proteins in this database have been characterized by their sequence-signatures, as defined by the InterPro classification. A statistical analysis performed on all possible combinations of sequence-signature pairs has identified those pairs that are over-represented in the database of yeast interacting proteins. It is demonstrated how the use of the correlated sequence-signatures as identifiers of interacting proteins can reduce significantly the search space, and enable directed experimental interaction screens.
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Affiliation(s)
- E Sprinzak
- Department of Molecular Genetics and Biotechnology, The Hebrew University--Hadassah Medical School, Jerusalem, 91120, Israel
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188
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Drees BL, Sundin B, Brazeau E, Caviston JP, Chen GC, Guo W, Kozminski KG, Lau MW, Moskow JJ, Tong A, Schenkman LR, McKenzie A, Brennwald P, Longtine M, Bi E, Chan C, Novick P, Boone C, Pringle JR, Davis TN, Fields S, Drubin DG. A protein interaction map for cell polarity development. J Cell Biol 2001; 154:549-71. [PMID: 11489916 PMCID: PMC2196425 DOI: 10.1083/jcb.200104057] [Citation(s) in RCA: 240] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Many genes required for cell polarity development in budding yeast have been identified and arranged into a functional hierarchy. Core elements of the hierarchy are widely conserved, underlying cell polarity development in diverse eukaryotes. To enumerate more fully the protein-protein interactions that mediate cell polarity development, and to uncover novel mechanisms that coordinate the numerous events involved, we carried out a large-scale two-hybrid experiment. 68 Gal4 DNA binding domain fusions of yeast proteins associated with the actin cytoskeleton, septins, the secretory apparatus, and Rho-type GTPases were used to screen an array of yeast transformants that express approximately 90% of the predicted Saccharomyces cerevisiae open reading frames as Gal4 activation domain fusions. 191 protein-protein interactions were detected, of which 128 had not been described previously. 44 interactions implicated 20 previously uncharacterized proteins in cell polarity development. Further insights into possible roles of 13 of these proteins were revealed by their multiple two-hybrid interactions and by subcellular localization. Included in the interaction network were associations of Cdc42 and Rho1 pathways with proteins involved in exocytosis, septin organization, actin assembly, microtubule organization, autophagy, cytokinesis, and cell wall synthesis. Other interactions suggested direct connections between Rho1- and Cdc42-regulated pathways; the secretory apparatus and regulators of polarity establishment; actin assembly and the morphogenesis checkpoint; and the exocytic and endocytic machinery. In total, a network of interactions that provide an integrated response of signaling proteins, the cytoskeleton, and organelles to the spatial cues that direct polarity development was revealed.
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Affiliation(s)
- B L Drees
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
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189
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Abstract
Extremely diverse, DNA-encoded libraries of peptides and proteins have been constructed that include a linkage between each polypeptide and the encoding DNA. Library members can be selected by virtue of a particular binding specificity, and their protein sequence can be deduced from the sequence of the cognate DNA. Such combinatorial biology methods have proven invaluable in both identifying natural protein-protein interactions and also in mapping the specificities and energetics of these interactions in fine detail.
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Affiliation(s)
- J Pelletier
- Université de Montréal, Département de Chimie, 2900 Edouard-Montpetit, Montréal, Québec H3C 3J7, Canada.
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190
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Abstract
Lumpy skin disease virus (LSDV), a member of the capripoxvirus genus of the Poxviridae, is the etiologic agent of an important disease of cattle in Africa. Here we report the genomic sequence of LSDV. The 151-kbp LSDV genome consists of a central coding region bounded by identical 2.4 kbp-inverted terminal repeats and contains 156 putative genes. Comparison of LSDV with chordopoxviruses of other genera reveals 146 conserved genes which encode proteins involved in transcription and mRNA biogenesis, nucleotide metabolism, DNA replication, protein processing, virion structure and assembly, and viral virulence and host range. In the central genomic region, LSDV genes share a high degree of colinearity and amino acid identity (average of 65%) with genes of other known mammalian poxviruses, particularly suipoxvirus, yatapoxvirus, and leporipoxviruses. In the terminal regions, colinearity is disrupted and poxvirus homologues are either absent or share a lower percentage of amino acid identity (average of 43%). Most of these differences involve genes and gene families with likely functions involving viral virulence and host range. Although LSDV resembles leporipoxviruses in gene content and organization, it also contains homologues of interleukin-10 (IL-10), IL-1 binding proteins, G protein-coupled CC chemokine receptor, and epidermal growth factor-like protein which are found in other poxvirus genera. These data show that although LSDV is closely related to other members of the Chordopoxvirinae, it contains a unique complement of genes responsible for viral host range and virulence.
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Affiliation(s)
- E R Tulman
- Plum Island Animal Disease Center, Agricultural Research Service, U.S. Department of Agriculture, Greenport, New York 11944, USA
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191
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Almazán F, Tscharke DC, Smith GL. The vaccinia virus superoxide dismutase-like protein (A45R) is a virion component that is nonessential for virus replication. J Virol 2001; 75:7018-29. [PMID: 11435582 PMCID: PMC114430 DOI: 10.1128/jvi.75.15.7018-7029.2001] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A characterization of the A45R gene from vaccinia virus (VV) strain Western Reserve is presented. The open reading frame is predicted to encode a 125-amino-acid protein (M(r), of 13,600) with 39% amino acid identity to copper-zinc superoxide dismutase (Cu-Zn SOD). Sequencing of the A45R gene from other orthopoxviruses, here and by others, showed that the protein is highly conserved in all viruses sequenced, including 16 strains of VV, 2 strains of cowpox virus, camelpox virus, and 4 strains of variola virus. In all cases the protein lacks key residues involved in metal ion binding that are important for the catalytic activity. The A45R protein was expressed in Escherichia coli, purified, and tested for SOD activity, but neither enzymatic nor inhibitory SOD activity was detected. Additionally, no virus-encoded SOD activity was detected in infected cells or purified virions. A monoclonal antibody raised against the A45R protein expressed in E. coli identified the A45R gene product as a 13.5-kDa protein that is expressed late during VV infection. Confocal microscopy of VV-infected cells indicated that the A45R protein accumulated predominantly in cytoplasmic viral factories. Electron microscopy and biochemical analyses showed that the A45R protein is incorporated into the virion core. A deletion mutant lacking the majority of the A45R gene and a revertant virus in which the deleted gene was restored were constructed and characterized. The growth properties of the deletion mutant virus were indistinguishable from those of wild-type and revertant viruses in all cell lines tested, including macrophages. Additionally, the virulence and pathogenicity of the three viruses were also comparable in murine and rabbit models of infection. A45R is unusual in being the first VV core protein described that affects neither virus replication nor virulence.
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Affiliation(s)
- F Almazán
- Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, United Kingdom
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192
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Legrain P, Wojcik J, Gauthier JM. Protein--protein interaction maps: a lead towards cellular functions. Trends Genet 2001; 17:346-52. [PMID: 11377797 DOI: 10.1016/s0168-9525(01)02323-x] [Citation(s) in RCA: 134] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The availability of complete genome sequences now permits the development of tools for functional biology on a proteomic scale. Several experimental approaches or in silico algorithms aim at clustering proteins into networks with biological significance. Among those, the yeast two-hybrid system is the technology of choice to detect protein-protein interactions. Recently, optimized versions were applied at a genomic scale, leading to databases on the web. However, as with any other 'genetic' assay, yeast two-hybrid assays are prone to false positives and false negatives. Here we discuss these various technologies, their general limitations and the potential advances they make possible, especially when in combination with other functional genomics or bioinformatics analyses.
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Affiliation(s)
- P Legrain
- Hybrigenics, 180 Avenue Daumesnil, Paris 75012, France.
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193
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Wagner A. The yeast protein interaction network evolves rapidly and contains few redundant duplicate genes. Mol Biol Evol 2001; 18:1283-92. [PMID: 11420367 DOI: 10.1093/oxfordjournals.molbev.a003913] [Citation(s) in RCA: 261] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
In this paper, the structure and evolution of the protein interaction network of the yeast Saccharomyces cerevisiae is analyzed. The network is viewed as a graph whose nodes correspond to proteins. Two proteins are connected by an edge if they interact. The network resembles a random graph in that it consists of many small subnets (groups of proteins that interact with each other but do not interact with any other protein) and one large connected subnet comprising more than half of all interacting proteins. The number of interactions per protein appears to follow a power law distribution. Within approximately 200 Myr after a duplication, the products of duplicate genes become almost equally likely to (1) have common protein interaction partners and (2) be part of the same subnetwork as two proteins chosen at random from within the network. This indicates that the persistence of redundant interaction partners is the exception rather than the rule. After gene duplication, the likelihood that an interaction gets lost exceeds 2.2 x 10(-3)/Myr. New interactions are estimated to evolve at a rate that is approximately three orders of magnitude smaller. Every 300 Myr, as many as half of all interactions may be replaced by new interactions.
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Affiliation(s)
- A Wagner
- Department of Biology, University of New Mexico, Albequerque, New Mexico 87131-1091, USA.
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194
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Kovacs GR, Vasilakis N, Moss B. Regulation of viral intermediate gene expression by the vaccinia virus B1 protein kinase. J Virol 2001; 75:4048-55. [PMID: 11287554 PMCID: PMC114150 DOI: 10.1128/jvi.75.9.4048-4055.2001] [Citation(s) in RCA: 26] [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
The B1 gene of vaccinia virus encodes a serine/threonine protein kinase that is expressed early after infection. Under nonpermissive conditions, temperature-sensitive mutants (ts2 and ts25) that map to B1 fail to efficiently replicate viral DNA. Our goal was to extend studies on the function of B1 by determining if the kinase is required for intermediate or late gene expression, two events that ordinarily depend on viral DNA replication. First, we established that early viral gene expression occurred at the nonpermissive temperature. By using a transfection procedure that circumvents the viral DNA replication requirement, we found that reporter genes regulated by an intermediate promoter were transcribed only under conditions permissive for expression of active B1. To assay late gene expression, the T7 RNA polymerase gene was inserted into the genome of ts25 to form ts25/T7. A DNA replication-independent late gene transcription system was established by cotransfecting plasmids containing T7 promoter-driven late gene transcription factors and a late promoter reporter gene into ts25/T7-infected cells. Late genes, unlike intermediate genes, were expressed at the nonpermissive temperature. Last, we showed that overexpression of B1 stimulated intermediate but inhibited late gene expression in cells infected with wild-type virus.
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Affiliation(s)
- G R Kovacs
- Department of Viral Vaccine Research, Wyeth-Lederle Vaccines, Pearl River, New York 10965, USA.
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195
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Hishigaki H, Nakai K, Ono T, Tanigami A, Takagi T. Assessment of prediction accuracy of protein function from protein--protein interaction data. Yeast 2001; 18:523-31. [PMID: 11284008 DOI: 10.1002/yea.706] [Citation(s) in RCA: 177] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
Functional prediction of open reading frames coded in the genome is one of the most important tasks in yeast genomics. Among a number of large-scale experiments for assigning certain functional classes to proteins, experiments determining protein-protein interaction are especially important because interacting proteins usually have the same function. Thus, it seems possible to predict the function of a protein when the function of its interacting partner is known. However, in vitro experiments often suffer from artifacts and a protein can often have multiple binding partners with different functions. We developed an objective prediction method that can systematically include the information of indirect interaction. Our method can predict the subcellular localization, the cellular role and the biochemical function of yeast proteins with accuracies of 72.7%, 63.6% and 52.7%, respectively. The prediction accuracy rises for proteins with more than three binding partners and thus we present the open prediction results for 16 such proteins.
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Affiliation(s)
- H Hishigaki
- Laboratory of Genome Database, Human Genome Center, Institute of Medical Science, The University of Tokyo, 4-6-1 Shirokanedai Minato-ku, Tokyo 108-8639, Japan
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196
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Yokoyama S, Matsuo Y, Hirota H, Kigawa T, Shirouzu M, Kuroda Y, Kurumizaka H, Kawaguchi S, Ito Y, Shibata T, Kainosho M, Nishimura Y, Inoue Y, Kuramitsu S. Structural genomics projects in Japan. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2001; 73:363-76. [PMID: 11063781 DOI: 10.1016/s0079-6107(00)00012-2] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Affiliation(s)
- S Yokoyama
- RIKEN Genomic Sciences Center, 1-7-22 Suehiro-cho, Tsurumi-ku, 230-0045, Yokohama, Japan.
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197
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Affiliation(s)
- S Fields
- Howard Hughes Medical Institute, Departments of Genetics and Medicine, University of Washington, Seattle, WA 98195, USA.
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198
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Ishii K, Moss B. Role of vaccinia virus A20R protein in DNA replication: construction and characterization of temperature-sensitive mutants. J Virol 2001; 75:1656-63. [PMID: 11160663 PMCID: PMC114074 DOI: 10.1128/jvi.75.4.1656-1663.2001] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Previous analyses of randomly generated, temperature-sensitive vaccinia virus mutants led to the mapping of DNA synthesis negative complementation groups to the B1R, D4R, D5R, and E9L genes. Evidence from the yeast two-hybrid system that the D4R and D5R proteins can interact with the A20R protein suggested that A20R was also involved in DNA replication. We found that the A20R gene was transcribed early after infection, consistent with such a role. To investigate the function of the A20R protein, targeted mutations were made by substituting alanines for charged amino acids occurring in 11 different clusters. Four mutants were not isolated, suggesting that they were lethal, two mutants exhibited no temperature sensitivity, two mutants exhibited partial temperature sensitivity, and two mutants formed no plaques or infectious virus at 39 degrees C. The two mutants with stringent phenotypes were further characterized. Temperature shift-up experiments indicated that the crucial period was between 6 and 12 h after infection, making it unlikely that the defect was in virus entry, early gene expression, or a late stage of virus assembly. Similar patterns of metabolically labeled viral early proteins were detected at permissive and nonpermissive temperatures, but one mutant showed an absence of late proteins under the latter conditions. Moreover, no viral DNA synthesis was detected when cells were infected with either stringent mutant at 39 degrees C. The previous yeast two-hybrid analysis together with the present characterization of A20R temperature-sensitive mutants suggested that the A20R, D4R, and D5R proteins are components of a multiprotein DNA replication complex.
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Affiliation(s)
- K Ishii
- Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA
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199
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Rain JC, Selig L, De Reuse H, Battaglia V, Reverdy C, Simon S, Lenzen G, Petel F, Wojcik J, Schächter V, Chemama Y, Labigne A, Legrain P. The protein-protein interaction map of Helicobacter pylori. Nature 2001; 409:211-5. [PMID: 11196647 DOI: 10.1038/35051615] [Citation(s) in RCA: 740] [Impact Index Per Article: 30.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
With the availability of complete DNA sequences for many prokaryotic and eukaryotic genomes, and soon for the human genome itself, it is important to develop reliable proteome-wide approaches for a better understanding of protein function. As elementary constituents of cellular protein complexes and pathways, protein-protein interactions are key determinants of protein function. Here we have built a large-scale protein-protein interaction map of the human gastric pathogen Helicobacter pylori. We have used a high-throughput strategy of the yeast two-hybrid assay to screen 261 H. pylori proteins against a highly complex library of genome-encoded polypeptides. Over 1,200 interactions were identified between H. pylori proteins, connecting 46.6% of the proteome. The determination of a reliability score for every single protein-protein interaction and the identification of the actual interacting domains permitted the assignment of unannotated proteins to biological pathways.
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200
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Bawden AL, Glassberg KJ, Diggans J, Shaw R, Farmerie W, Moyer RW. Complete genomic sequence of the Amsacta moorei entomopoxvirus: analysis and comparison with other poxviruses. Virology 2000; 274:120-39. [PMID: 10936094 DOI: 10.1006/viro.2000.0449] [Citation(s) in RCA: 114] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The genome of the genus B entomopoxvirus from Amsacta moorei (AmEPV) was sequenced and found to contain 232,392 bases with 279 unique open reading frames (ORFs) of greater than 60 amino acids. The central core of the viral chromosome is flanked by 9.4-kb inverted terminal repeats (ITRs), each of which contains 13 ORFs, raising the total number of ORFs within the viral chromosome to 292. ORFs with no known homology to other poxvirus genes were shown to constitute 33.6% of the viral genome. Approximately 28.6% of the AmEPV genome encodes homologs of the mammalian poxvirus colinear core genes, which are found dispersed throughout the AmEPV chromosome. There is also no significant gene order conservation between AmEPV and the orthopteran genus B poxvirus of Melanoplus sanguinipes (MsEPV). Novel AmEPV genes include those encoding a putative ABC transporter and a Kunitz-motif protease inhibitor. The most unusual feature of the AmEPV genome relates to the viral encoded poly(A) polymerase. In all other poxviruses this heterodimeric enzyme consists of a single large and a single small subunit. However, AmEPV appears to encode one large and two distinct small poly(A) polymerase subunits. AmEPV is one of the few entomopoxviruses which can be grown and manipulated in cell culture. The complete genomic sequence of AmEPV paves the way for an understanding and comparison of the molecular properties and pathogenesis between the entomopoxviruses of insects and the more intensively studied vertebrate poxviruses.
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Affiliation(s)
- A L Bawden
- Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, Florida 32610, USA
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