Conservation of edge essentiality profiles in metabolic networks across species

Abstract

Reactions involved in cellular metabolism form a complex network susceptible to targeted attacks. Recent experiments show that several descriptors of edge essentiality correlate well with lethality of silencing corresponding genes in a model organism, opening path to identifying targets for antimicrobial drugs that would disrupt network functioning in bacteria. However, correlation of high essentiality with experiment is necessary but not sufficient for a descriptor to be useful. Also, the essentialities of corresponding edges have to differ markedly between pathogens and hosts, to yield minimal effect on the latter. Here, we analyse similarity of profiles of several edge essentiality measures across multiple species. We show that local measures, based on degrees of a substrate and a product linked by the edge, or on the alternative paths connecting the two, are evolutionarily conserved within bacteria, archaea and eukaryotes, but also differ between these groups, leading to isolated clusters of species. Furthermore, comparison with a global topological measure, the relative decrease in network efficiency upon edge removal, shows that metabolic networks are more conserved locally than globally. © 2009 ICST Institute for Computer Sciences, Social Informatics and Telecommunications Engineering.