We have constructed a natural products database, "RIKEN Natural Products Encyclopedia (RIKEN NPEdia)", as an informatics part of chemical resource bank, "the RIKEN Natural Products Depository (RIKEN NPDepo)". Approximately 25,000 compound data are now listed in NPEdia, some of which were transferred from "KNApSAcK", a secondary metabolites database constructed by Prof. Kanaya and his colleagues (http://kanaya.aist-nara.ac.jp/KNApSAcK/, http://prime.psc.riken.jp/ (mirror site)). Compounds listed in NPEdia are mainly secondary metabolites isolated from actinomycetes, fungi, plants and other organisms. Each compound data consists of molecular structure, origin, and physico-chemical and biological properties. MOL files can be also downloaded. Ultra-Violet, MS/MS and NMR spectra will also be included in the near future. This database involves three functions: (1) searching for compounds, (2) registering compound data and (3) co-operating in compound-order system. We are now trying to integrate metabolites with metabolic pathway maps, protein-protein interaction maps, and chemical genomics maps (relationship between metabolic pathways and small molecules "bioprobes" interacting them). We think NPEdia should be a useful database friendly to researchers in various research fields. The details and latest news about NPEdia are described on the website (http://npd.riken.jp/).

The four electron transfer energy metabolism systems, photosynthesis, aerobic respiration, denitrification, and sulfur respiration, are thought to be evolutionarily related because of the similarity of electron transfer patterns and the existence of some homologous proteins. How these systems have evolved is elusive. We therefore conducted a comprehensive homology search using PSI-BLAST, and phylogenetic analyses were conducted for the three homologous groups (groups 1-3) based on multiple alignments of domains defined in the Pfam database. There are five electron transfer types important for catalytic reaction in group 1, and many proteins bind molybdenum. Deletions of two domains led to loss of the function of binding molybdenum and ferredoxin, and these deletions seem to be critical for the electron transfer pattern changes in group 1. Two types of electron transfer were found in group 2, and all its member proteins bind siroheme and ferredoxin. Insertion of the pyridine nucleotide disulfide oxidoreductase domain seemed to be the critical point for the electron transfer pattern change in this group. The proteins belonging to group 3 are all flavin enzymes, and they bind flavin adenine dinucleotide (FAD) or flavin mononucleotide (FMN). Types of electron transfer in this group are divergent, but there are two common characteristics. NAD(P)H works as an electron donor or acceptor, and FAD or FMN transfers electrons from/to NAD(P)H. Electron transfer functions might be added to these common characteristics by the addition of functional domains through the evolution of group 3 proteins. Based on the phylogenetic analyses in this study and previous studies, we inferred the phylogeny of the energy metabolism systems as follows: photosynthesis (and possibly aerobic respiration) and the sulfur/nitrogen assimilation system first diverged, then the sulfur/nitrogen dissimilation system was produced from the latter system.

No abstract