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The PeroxiBase (http://peroxibase.toulouse.inra.fr/) is a specialized database devoted to peroxidases' families, which are major actors of stress responses. In addition to the increasing number of sequences and the complete modification of the Web interface, new analysis tools and functionalities have been developed since the previous publication in the NAR database issue. Nucleotide sequences and graphical representation of the gene structure can now be included for entries containing genomic cross-references. An expert semi-automatic annotation strategy is being developed to generate new entries from genomic sequences and from EST libraries. Plus, new internal and automatic controls have been included to improve the quality of the entries. To compare gene structure organization among families' members, two new tools are available, CIWOG to detect common introns and GECA to visualize gene structure overlaid with sequence conservation. The multicriteria search tool was greatly improved to allow simple and combined queries. After such requests or a BLAST search, different analysis processes are suggested, such as multiple alignments with ClustalW or MAFFT, a platform for phylogenetic analysis and GECA's display in association with a phylogenetic tree. Finally, we updated our family specific profiles implemented in the PeroxiScan tool and made new profiles to consider new sub-families.

Peroxidases (EC 1.11.1.x), which are encoded by small or large multigenic families, are involved in several important physiological and developmental processes. They use various peroxides as electron acceptors to catalyse a number of oxidative reactions and are present in almost all living organisms. We have created a peroxidase database (http://peroxibase.isb-sib.ch) that contains all identified peroxidase-encoding sequences (about 6000 sequences in 940 organisms). They are distributed between 11 superfamilies and about 60 subfamilies. All the sequences have been individually annotated and checked. PeroxiBase can be consulted using six major interlink sections 'Classes', 'Organisms', 'Cellular localisations', 'Inducers', 'Repressors' and 'Tissue types'. General documentation on peroxidases and PeroxiBase is accessible in the 'Documents' section containing 'Introduction', 'Class description', 'Publications' and 'Links'. In addition to the database, we have developed a tool to classify peroxidases based on the PROSITE profile methodology. To improve their specificity and to prevent overlaps between closely related subfamilies the profiles were built using a new strategy based on the silencing of residues. This new profile construction method and its discriminatory capacity have been tested and validated using the different peroxidase families and subfamilies present in the database. The peroxidase classification tool called PeroxiScan is accessible at the following address: http://peroxibase.isb-sib.ch/peroxiscan.php.

Peroxidases are enzymes that are implicated in several biological processes and are detected in all living organisms. The increasing number of sequencing projects and the poor quality of annotation justified the creation of an efficient tool that was suitable for collecting and annotating the huge quantity of data. Started in 2004 to collect only class III peroxidases, PeroxiBase has undergone important updates since then and, currently, the majority of peroxidase sequences from all kingdoms of life is stored in the database. In addition, the web site (http://peroxibase.isb-sib.ch) provides a series of bioinformatics tools and facilities suitable for analysing these stored sequences. In particular, the high number of isoforms in each organism makes phylogenetic studies extremely useful to elucidate the complex evolution of these enzymes, not only within the plant kingdom but also between the different kingdoms. This paper provides a general overview of PeroxiBase, focusing on its tools and the stored data. The main goal is to give researchers some guidelines to extract classified and annotated sequences from the data base in a quick and easy way in order to perform alignments and phylogenetic analysis. The description of the database is accompanied by the updates we have recently carried out in order to improve its completeness and make it more user-friendly.

Peroxidases (EC 1.11.1.x), which are encoded by small or large multigenic families, are involved in several important physiological and developmental processes. Analyzing their evolution and their distribution among various phyla could certainly help to elucidate the mystery of their extremely widespread and diversified presence in almost all living organisms. PeroxiBase was originally created for the exhaustive collection of class III peroxidase sequences from plants (Bakalovic, N., Passardi, F., et al., 2006. PeroxiBase: a class III plant peroxidase database. Phytochemistry 67, 534-539). The extension of the class III peroxidase database to all proteins capable to reduce peroxide molecules appears as a necessity. Our database contains haem and non-haem peroxidase sequences originated from annotated or not correctly annotated sequences deposited in the main repositories such as GenBank or UniProt KnowledgeBase. This new database will allow obtaining a global overview of the evolution the protein families and superfamilies capable of peroxidase reaction. In this rapidly growing field, there is a need for continual updates and corrections of the peroxidase protein sequences. Following the lack of unified nomenclature, we also introduced a unique abbreviation for each different family of peroxidases. This paper thus aims to report the evolution of the PeroxiBase database, which is freely accessible through a web server (http://peroxibase.isb-sib.ch). In addition to new categories of peroxidases, new specific tools have been created to facilitate query, classification and submission of peroxidase sequences.

Class III plant peroxidases (EC 1.11.1.7), which are encoded by multigenic families in land plants, are involved in several important physiological and developmental processes. Their varied functions are not yet clearly determined, but their characterization will certainly lead to a better understanding of plant growth, differentiation and interaction with the environment, and hence to many exciting applications. Since there is currently no central database for plant peroxidase sequences and many plant sequences are not deposited in the EMBL/GenBank/DDBJ repository or the UniProt KnowledgeBase, this prevents researchers from easily accessing all peroxidase sequences. Furthermore, gene expression data are poorly covered and annotations are inconsistent. In this rapidly moving field, there is a need for continual updating and correction of the peroxidase superfamily in plants. Moreover, consolidating information about peroxidases will allow for comparison of peroxidases between species and thus significantly help making correlations of function, structure or phylogeny. We report a new database (PeroxiBase) accessible through a web server with specific tools dedicated to facilitate query, classification and submission of peroxidase sequences. Recent developments in the field of plant peroxidase are also mentioned.