Maltsev Natalia, Glass Elizabeth M, Ovchinnikova Galina, Gu Zhenglong
Argonne National Laboratory, Mathematics and Computer Science Division, Argonne, IL 60439, USA.
J Biochem. 2005 Feb;137(2):177-87. doi: 10.1093/jb/mvi017.
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. Uninterrupted flow of energy and precursor metabolites through the pathways of central metabolism via glycolysis (EMP), pentose phosphate shunt (PPS), and the tricarboxylic acid (TCA) cycle are ensured by a 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 for increasing the robustness of the system. The robustness of the pathways of central metabolism is apparently higher than that of the other parts of metabolism, because of its exceptional importance to the organism's vitality. The proportion of duplicated viable genes also is substantially larger in central metabolism than that in a pool of other metabolic genes.
酿酒酵母采用的适应性策略赋予了其中心代谢的稳健性和适应性。由于酵母的中心代谢在酶学和遗传学层面已得到充分研究，它成为了一个绝佳的系统，可用于评估重复基因和替代代谢途径作为中心代谢抵御无效突变稳定性的可能机制的相对作用。酵母似乎采用了多种机制来确保其中心代谢的功能稳健性。通过糖酵解（EMP）、磷酸戊糖途径（PPS）和三羧酸（TCA）循环等中心代谢途径，能量和前体代谢物的不间断流动由多种适应性机制来确保。其中最重要的机制之一似乎是基因复制事件，这些事件产生了许多在可变的环境和生理条件下起作用的同工酶。替代途径是增加系统稳健性的另一个重要机制。中心代谢途径的稳健性明显高于代谢的其他部分，因为它对生物体的活力至关重要。中心代谢中重复的存活基因比例也比其他代谢基因库中的比例大得多。
