Metabolic network destruction: Relating topology to robustness

Biological networks exhibit intriguing topological properties such as small-worldness. In this paper, we investigate whether the topology of a particular type of biological network, ametabolic network, is related to its robustness.Wedo so byperturbing ametabolic system in silico, one reaction at a time and studying the correlations between growth, as predicted by flux balance analysis, and a number of topological metrics, as computed from three network representations of the metabolic system. We find that a small number of metrics correlate with growth and that only one of the network representations stands out in terms of correlated metrics. The most correlated metrics point to the importance of hub nodes in this network, so-called ‘‘currency metabolites’’. Since they are responsible for interconnecting distant functional modules in the network, they are important points in the network for predicting if reaction removal affects growth. A second set of correlations in contrast is related to ‘‘loner’’ nodes that uniquely connect important pathways and thus correspond to essential steps in metabolism. © 2011 Elsevier Ltd. All rights reserved.