N. Maltsev, E. M. Glass, G. Ovchinnikova, and Z. Gu, "Molecular Mechanisms Involved in Robustness of Yeast Central Metabolism Against Null Mutations," Preprint ANL/MCS-P1198-0904, September 2004. [pdf]
Adaptive strategies employed by the yeast Saccharomyces cerevisiae provide robustness and adaptability of its central metabolism. Since central metabolism in yeast has been well studied at the enzymatic and genetic levels, it represents an excellent system for evaluating the relative roles of duplicate genes and alternative metabolic pathways as possible mechanisms for the stability of central metabolism against null mutations. Yeast appears to employ a variety of mechanisms to ensure functional robustness of its central metabolism. Un-interrupted flow of energy and precursor metabolites through the pathways of central metabolism via glycolysis (EMP), pentose phosphate pathway (PPP), and the TCA (tricarboxylic acid) cycle are ensured by variety of adaptive mechanisms. One of the most significant mechanisms appears to be gene duplication events that have produced a number of isozymes functioning under variable environmental and physiological conditions. Alternative pathways represent another important mechanism of increasing of the robustness of the system. The robustness of the pathways of central metabolism is apparently higher than that of the other parts of metabolism, due to its exceptional importance to organismís vitality. The proportion of duplicated viable genes in central metabolism is substantially larger in central metabolism than that in a pool of other metabolic genes.