[Show abstract][Hide abstract] ABSTRACT: BlastKOALA and GhostKOALA are automatic annotation servers for genome and metagenome sequences, which perform KEGG Orthology (KO) assignments to characterize individual gene functions and reconstruct KEGG pathways, BRITE hierarchies and KEGG modules to infer high-level functions of the organism or the ecosystem. Both servers are made freely available at the KEGG website (http://www.kegg.jp/blastkoala/). In BlastKOALA the KO assignment is done by a modified version of the internally used KOALA algorithm after the BLAST search against a non-redundant dataset of pangenome sequences at the species, genus or family level, which is generated from the KEGG GENES database by retaining the KO content of each taxonomic category. In GhostKOALA, which utilizes more rapid GHOSTX for database search and is suitable for metagenome annotation, the pangenome dataset is supplemented with CD-HIT clusters including those for viral genes. The result files may be downloaded and manipulated for further KEGG Mapper analysis, such as comparative pathway analysis using multiple BlastKOALA results.
Journal of Molecular Biology 11/2015; DOI:10.1016/j.jmb.2015.11.006 · 4.33 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: KEGG (http://www.kegg.jp/ or http://www.genome.jp/kegg/) is an integrated database resource for biological interpretation of genome sequences and other high-throughput data. Molecular functions of genes and proteins are associated with ortholog groups and stored in the KEGG Orthology (KO) database. The KEGG pathway maps, BRITE hierarchies and KEGG modules are developed as networks of KO nodes, representing high-level functions of the cell and the organism. Currently, more than 4000 complete genomes are annotated with KOs in the KEGG GENES database, which can be used as a reference data set for KO assignment and subsequent reconstruction of KEGG pathways and other molecular networks. As an annotation resource, the following improvements have been made. First, each KO record is re-examined and associated with protein sequence data used in experiments of functional characterization. Second, the GENES database now includes viruses, plasmids, and the addendum category for functionally characterized proteins that are not represented in complete genomes. Third, new automatic annotation servers, BlastKOALA and GhostKOALA, are made available utilizing the non-redundant pangenome data set generated from the GENES database. As a resource for translational bioinformatics, various data sets are created for antimicrobial resistance and drug interaction networks.
Nucleic Acids Research 10/2015; DOI:10.1093/nar/gkv1070 · 9.11 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: This chapter describes the KEGG GLYCAN database of the KEGG resource, including descriptions of links to the other databases in KEGG. In particular, KEGG GLYCAN consists of glycan structures, with links to glycogenes, orthologs, reactions, pathways, drugs, diseases, and others, all within the KEGG resources. A number of analytical tools are also available, including the composite structure map (CSM), KegDraw, KCam, and GECS. These databases and tools will be described along with simple examples of their usage.
[Show abstract][Hide abstract] ABSTRACT: Genomics is faced with the issue of many partially annotated putative enzyme-encoding genes for which activities have not yet been verified, while metabolomics is faced with the issue of many putative enzyme reactions for which full equations have not been verified. Knowledge of enzymes has been collected by IUBMB, and has been made public as the Enzyme List. To date, however, the terminology of the Enzyme List has not been assessed comprehensively by bioinformatics studies. Instead, most of the bioinformatics studies simply use the identifiers of the enzymes, i.e. the Enzyme Commission (EC) numbers. We investigated the actual usage of terminology throughout the Enzyme List, and demonstrated that the partial characteristics of reactions cannot be retrieved by simply using EC numbers. Thus, we developed a novel ontology, named PIERO, for annotating biochemical transformations as follows. First, the terminology describing enzymatic reactions was retrieved from the Enzyme List, and was grouped into those related to overall reactions and biochemical transformations. Consequently, these terms were mapped onto the actual transformations taken from enzymatic reaction equations. This ontology was linked to Gene Ontology (GO) and EC numbers, allowing the extraction of common partial reaction characteristics from given sets of orthologous genes and the elucidation of possible enzymes from the given transformations. Further future development of the PIERO ontology should enhance the Enzyme List to promote the integration of genomics and metabolomics.
Journal of Bioinformatics and Computational Biology 10/2014; 12(06):1442001. DOI:10.1142/S0219720014420013 · 0.78 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: DINIES (drug–target interaction network inference engine based on supervised analysis) is a web server for predicting unknown
drug–target interaction networks from various types of biological data (e.g. chemical structures, drug side effects, amino
acid sequences and protein domains) in the framework of supervised network inference. The originality of DINIES lies in prediction
with state-of-the-art machine learning methods, in the integration of heterogeneous biological data and in compatibility with
the KEGG database. The DINIES server accepts any ‘profiles’ or precalculated similarity matrices (or ‘kernels’) of drugs and
target proteins in tab-delimited file format. When a training data set is submitted to learn a predictive model, users can
select either known interaction information in the KEGG DRUG database or their own interaction data. The user can also select
an algorithm for supervised network inference, select various parameters in the method and specify weights for heterogeneous
data integration. The server can provide integrative analyses with useful components in KEGG, such as biological pathways,
functional hierarchy and human diseases. DINIES (http://www.genome.jp/tools/dinies/) is publicly available as one of the genome analysis tools in GenomeNet.
Nucleic Acids Research 05/2014; DOI:10.1093/nar/gku337 · 9.11 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The IUBMB׳s Enzyme List gives a valuable library of the individual experimental facts on enzyme activities, providing the standard classification and nomenclature of enzymes. Empirical knowledge about the relationships between the enzyme protein sequences (or structures) and their functions (the capability of catalyzing chemical reactions) has been accumulating in public literatures and databases. This provides a complementary approach to standardize and organize enzyme data, i.e., predicting the possible enzymes, reactions and metabolites that remain to be identified experimentally. Thus, we suggest the necessity of classifying enzymes based on the evidence and different perspectives obtained from various experimental works. The KEGG (Kyoto Encyclopedia of Genes and Genomes) database describes enzymes from many different viewpoints including; the IUBMB׳s enzyme nomenclature/classification (EC numbers), the similarity group of enzyme reactions (KEGG Reaction Class; RCLASS) based solely on the chemical structure transformation patterns, and the similarity groups of enzyme genes (KEGG Orthology; KO) based on the orthologous groups that can be mapped to the KEGG PATHWAY and BRITE functional hierarchy. Some unique identifiers were additionally introduced to the KEGG database other than the EC numbers established by IUBMB. R, RP and RC numbers are given to distinguish reactions, reactant pairs and RCLASS, respectively. Genes, including enzyme genes, have their own ID numbers in specific organisms, and they are classified into ortholog groups that are identified by K numbers. In this review, we explain the concept and methodology of this formulation with some concrete example cases. We propose it beneficial to create a standard classification scheme that deals with both experimentally identified and theoretically predicted enzymes.
[Show abstract][Hide abstract] ABSTRACT: In order to develop hypothesis on unknown metabolic pathways, biochemists frequently rely on literature that uses a free-text format to describe functional groups or substructures. In computational chemistry or cheminformatics, molecules are typically represented by chemical descriptors, i.e., vectors that summarize information on its various properties. However, it is difficult to interpret these chemical descriptors since they are not directly linked to the terminology of functional groups or substructures that the biochemists use.
In this study, we used KEGG Chemical Function (KCF) format to computationally describe biochemical substructures in seven attributes that resemble biochemists' way of dealing with substructures.
We established KCF-S (KCF-and-Substructures) format as an additional structural information of KCF. Applying KCF-S revealed the specific appearance of substructures from various datasets of molecules that describes the characteristics of the respective datasets. Structure-based clustering of molecules using KCF-S resulted the clusters in which molecular weights and structures were less diverse than those obtained by conventional chemical fingerprints. We further applied KCF-S to find the pairs of molecules that are possibly converted to each other in enzymatic reactions, and KCF-S clearly improved predictive performance than that presented previously.
KCF-S defines biochemical substructures with keeping interpretability, suggesting the potential to apply more studies on chemical bioinformatics. KCF and KCF-S can be automatically converted from Molfile format, enabling to deal with molecules from any data sources.
[Show abstract][Hide abstract] ABSTRACT: In the hierarchy of data, information and knowledge, computational methods play a major role in the initial processing of
data to extract information, but they alone become less effective to compile knowledge from information. The Kyoto Encyclopedia
of Genes and Genomes (KEGG) resource (http://www.kegg.jp/ or http://www.genome.jp/kegg/) has been developed as a reference knowledge base to assist this latter process. In particular, the KEGG pathway maps are
widely used for biological interpretation of genome sequences and other high-throughput data. The link from genomes to pathways
is made through the KEGG Orthology system, a collection of manually defined ortholog groups identified by K numbers. To better
automate this interpretation process the KEGG modules defined by Boolean expressions of K numbers have been expanded and improved.
Once genes in a genome are annotated with K numbers, the KEGG modules can be computationally evaluated revealing metabolic
capacities and other phenotypic features. The reaction modules, which represent chemical units of reactions, have been used
to analyze design principles of metabolic networks and also to improve the definition of K numbers and associated annotations.
For translational bioinformatics, the KEGG MEDICUS resource has been developed by integrating drug labels (package inserts)
used in society.
Nucleic Acids Research 11/2013; 42(D1). DOI:10.1093/nar/gkt1076 · 9.11 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Despite wide-spread consensus on the need to transform toxicology and risk assessment in order to keep pace with technological and computational changes that have revolutionized the life sciences, there remains much work to be done to achieve the vision of toxicology based on a mechanistic foundation. To this end, a workshop was organized to explore one key aspect of this transformation - the development of Pathways of Toxicity as a key tool for hazard identification based on systems biology. Several issues were discussed in depth in the workshop: The first was the challenge of formally defining the concept of a Pathway of Toxicity (PoT), as distinct from, but complementary to, other toxicological pathway concepts such as mode of action (MoA). The workshop came up with a preliminary definition of PoT as "A molecular definition of cellular processes shown to mediate adverse outcomes of toxicants". It is further recognized that normal physiological pathways exist that maintain homeostasis and these, sufficiently perturbed, can become PoT. Second, the workshop sought to define the adequate public and commercial resources for PoT information, including data, visualization, analyses, tools, and use-cases, as well as the kinds of efforts that will be necessary to enable the creation of such a resource. Third, the workshop explored ways in which systems biology approaches could inform pathway annotation, and which resources are needed and available that can provide relevant PoT information to the diverse user communities.
[Show abstract][Hide abstract] ABSTRACT: The KEGG pathway maps are widely used as a reference data set for inferring high-level functions of the organism or the ecosystem from its genome or metagenome sequence data. The KEGG modules, which are tighter functional units often corresponding to subpathways in the KEGG pathway maps, are designed for better automation of genome interpretation. Each KEGG module is represented by a simple Boolean expression of KEGG Orthology (KO) identifiers (K numbers), enabling automatic evaluation of the completeness of genes in the genome. Here we focus on metabolic functions and introduce reaction modules for improving annotation and signature modules for inferring metabolic capacity.We also describe how genome annotation is performed in KEGG using the manually created KO database and the computationally generated SSDB database. The resulting KEGG GENES database with KO (K number) annotation is a reference sequence database to be compared for automated annotation and interpretation of newly determined genomes.
[Show abstract][Hide abstract] ABSTRACT: There is a tendency that a unit of enzyme genes in an operon-like structure in the prokaryotic genome encodes enzymes that catalyze a series of consecutive reactions in a metabolic pathway. Our recent analysis shows that this and other genomic units correspond to chemical units reflecting chemical logic of organic reactions. From all known metabolic pathways in the KEGG database chemical units, called reaction modules, we identified the conserved sequences of chemical structure transformation patterns of small molecules. The extracted patterns suggest co-evolution of genomic units and chemical units. While the core of the metabolic network may have evolved with mechanisms involving individual enzymes and reactions, its extension may have been driven by modular units of enzymes and reactions.
[Show abstract][Hide abstract] ABSTRACT: The metabolic network is both a network of chemical reactions and a network of enzymes that catalyze reactions. Towards better understanding of this duality in the evolution of the metabolic network, we developed a method to extract conserved sequences of reactions called reaction modules from the analysis of chemical compound structure transformation patterns in all known metabolic pathways stored in the KEGG PATHWAY database. The extracted reaction modules are repeatedly used as if they are building blocks of the metabolic network and contain chemical logic of organic reactions. Furthermore, the reaction modules often correspond to traditional pathway modules defined as sets of enzymes in the KEGG MODULE database and sometimes to operon-like gene clusters in prokaryotic genomes. We identified well-conserved, possibly ancient, reaction modules involving 2-oxocarboxylic acids. The chain extension module that appears as the tricarboxylic acid reaction sequence in the TCA cycle is now shown to be used in other pathways together with different types of modification modules. We also identified reaction modules and their connection patterns for aromatic ring cleavages in microbial biodegradation pathways, which are most characteristic in terms of both distinct reaction sequences and distinct gene clusters. The modular architecture of biodegradation modules will have a potential for predicting degradation pathways of xenobiotic compounds. The collection of these and many other reaction modules is made available as part of the KEGG database.
Journal of Chemical Information and Modeling 02/2013; 53(3). DOI:10.1021/ci3005379 · 3.74 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: KEGG ( http://www.genome.jp/kegg/ ) is an integrated database resource for linking genomes or molecular datasets to molecular networks (pathways, etc.) representing higher-level systemic functions of the cell, the organism, and the ecosystem. Major efforts have been undertaken for capturing and representing experimental knowledge as manually drawn KEGG pathway maps and for genome-based generalization of experimental knowledge through the KEGG Orthology (KO) system. Current knowledge on diseases and drugs has also been integrated in the KEGG pathway maps, especially in terms of known disease genes and drug targets. Thus, KEGG can be used as a reference knowledge base for integration and interpretation of large-scale datasets generated by high-throughput experimental technologies, as well for finding their practical values. Here we give an introduction to the KEGG Mapper tools, especially for understanding disease mechanisms and adverse drug interactions.
[Show abstract][Hide abstract] ABSTRACT: Background
One of the main goals of genomic analysis is to elucidate the comprehensive functions (functionome) in individual organisms or a whole community in various environments. However, a standard evaluation method for discerning the functional potentials harbored within the genome or metagenome has not yet been established. We have developed a new evaluation method for the potential functionome, based on the completion ratio of Kyoto Encyclopedia of Genes and Genomes (KEGG) functional modules.
Distribution of the completion ratio of the KEGG functional modules in 768 prokaryotic species varied greatly with the kind of module, and all modules primarily fell into 4 patterns (universal, restricted, diversified and non-prokaryotic modules), indicating the universal and unique nature of each module, and also the versatility of the KEGG Orthology (KO) identifiers mapped to each one. The module completion ratio in 8 phenotypically different bacilli revealed that some modules were shared only in phenotypically similar species. Metagenomes of human gut microbiomes from 13 healthy individuals previously determined by the Sanger method were analyzed based on the module completion ratio. Results led to new discoveries in the nutritional preferences of gut microbes, believed to be one of the mutualistic representations of gut microbiomes to avoid nutritional competition with the host.
The method developed in this study could characterize the functionome harbored in genomes and metagenomes. As this method also provided taxonomical information from KEGG modules as well as the gene hosts constructing the modules, interpretation of completion profiles was simplified and we could identify the complementarity between biochemical functions in human hosts and the nutritional preferences in human gut microbiomes. Thus, our method has the potential to be a powerful tool for comparative functional analysis in genomics and metagenomics, able to target unknown environments containing various uncultivable microbes within unidentified phyla.
[Show abstract][Hide abstract] ABSTRACT: The identification of orthologous genes in an increasing number of fully sequenced genomes is a challenging issue in recent genome science. Here we present KEGG OC (http://www.genome.jp/tools/oc/), a novel database of ortholog clusters (OCs). The current version of KEGG OC contains 1 176 030 OCs, obtained by clustering 8 357 175 genes in 2112 complete genomes (153 eukaryotes, 1830 bacteria and 129 archaea). The OCs were constructed by applying the quasi-clique-based clustering method to all possible protein coding genes in all complete genomes, based on their amino acid sequence similarities. It is computationally efficient to calculate OCs, which enables to regularly update the contents. KEGG OC has the following two features: (i) It consists of all complete genomes of a wide variety of organisms from three domains of life, and the number of organisms is the largest among the existing databases; and (ii) It is compatible with the KEGG database by sharing the same sets of genes and identifiers, which leads to seamless integration of OCs with useful components in KEGG such as biological pathways, pathway modules, functional hierarchy, diseases and drugs. The KEGG OC resources are accessible via OC Viewer that provides an interactive visualization of OCs at different taxonomic levels.
[Show abstract][Hide abstract] ABSTRACT: We sequenced the genome of Theileria orientalis, a tick-borne apicomplexan protozoan parasite of cattle. The focus of this study was a comparative genome analysis of T. orientalis relative to other highly pathogenic Theileria species, T. parva and T. annulata. T. parva and T. annulata induce transformation of infected cells of lymphocyte or macrophage/monocyte lineages; in contrast, T. orientalis does not induce uncontrolled proliferation of infected leukocytes and multiplies predominantly within infected erythrocytes. While synteny across homologous chromosomes of the three Theileria species was found to be well conserved overall, subtelomeric structures were found to differ substantially, as T. orientalis lacks the large tandemly arrayed subtelomere-encoded variable secreted protein-encoding gene family. Moreover, expansion of particular gene families by gene duplication was found in the genomes of the two transforming Theileria species, most notably, the TashAT/TpHN and Tar/Tpr gene families. Gene families that are present only in T. parva and T. annulata and not in T. orientalis, Babesia bovis, or Plasmodium were also identified. Identification of differences between the genome sequences of Theileria species with different abilities to transform and immortalize bovine leukocytes will provide insight into proteins and mechanisms that have evolved to induce and regulate this process. The T. orientalis genome database is available at http://totdb.czc.hokudai.ac.jp/.
[Show abstract][Hide abstract] ABSTRACT: KEGG (Kyoto Encyclopedia of Genes and Genomes) is a bioinformatics resource for understanding the functions and utilities of cells and organisms from both high-level and genomic perspectives. It is a self-sufficient, integrated resource consisting of genomic, chemical, and network information, with cross-references to numerous outside databases. The genomic and chemical information is a complete set of building blocks (genes and molecules) and the network information includes molecular wiring diagrams (interaction/reaction networks) and hierarchical classifications (relation networks) to represent high-level functions. This unit describes protocols for using KEGG, focusing on molecular network information in KEGG PATHWAY, KEGG BRITE, and KEGG MODULE, perturbed molecular networks in KEGG DISEASE and KEGG DRUG, molecular building block information in KEGG GENES and KEGG LIGAND, and a mechanism for linking genomes to molecular networks in KEGG ORTHOLOGY (KO). All of these many protocols enable the user to take advantage of the full breadth of the functionality provided by KEGG.
Current protocols in bioinformatics / editoral board, Andreas D. Baxevanis ... [et al.] 06/2012; Chapter 1:Unit1.12. DOI:10.1002/0471250953.bi0112s38
[Show abstract][Hide abstract] ABSTRACT: Gene network inference engine based on supervised analysis (GENIES) is a web server to predict unknown part of gene network from various types of genome-wide data in the framework of supervised network inference. The originality of GENIES lies in the construction of a predictive model using partially known network information and in the integration of heterogeneous data with kernel methods. The GENIES server accepts any 'profiles' of genes or proteins (e.g. gene expression profiles, protein subcellular localization profiles and phylogenetic profiles) or pre-calculated gene-gene similarity matrices (or 'kernels') in the tab-delimited file format. As a training data set to learn a predictive model, the users can choose either known molecular network information in the KEGG PATHWAY database or their own gene network data. The user can also select an algorithm of supervised network inference, choose various parameters in the method, and control the weights of heterogeneous data integration. The server provides the list of newly predicted gene pairs, maps the predicted gene pairs onto the associated pathway diagrams in KEGG PATHWAY and indicates candidate genes for missing enzymes in organism-specific metabolic pathways. GENIES (http://www.genome.jp/tools/genies/) is publicly available as one of the genome analysis tools in GenomeNet.
Nucleic Acids Research 05/2012; 40(Web Server issue):W162-7. DOI:10.1093/nar/gks459 · 9.11 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In this chapter, we demonstrate the usability of the KEGG (Kyoto encyclopedia of genes and genomes) databases and tools, especially focusing on the visualization of the omics data. The desktop application KegArray and many Web-based tools are tightly integrated with the KEGG knowledgebase, which helps visualize and interpret large amount of data derived from high-throughput measurement techniques including microarray, metagenome, and metabolome analyses. Recently developed resources for human disease, drug, and plant research are also mentioned.