Kurlandzka A, Rosenzweig R F, Adams J
Department of Biology, University of Michigan, Ann Arbor 48109.
Mol Biol Evol. 1991 May;8(3):261-81. doi: 10.1093/oxfordjournals.molbev.a040650.
A population of Escherichia coli initiated with a single clone developed extensive morphological and physiological polymorphism after being maintained for 773 generations in glucose-limited continuous culture. To understand the mechanisms of adaptation to this environment, total protein patterns of four adaptive clones and of the parent strains were examined by two-dimensional gel electrophoresis. Approximately 20% of the proteins (approximately 160 in absolute numbers) showed significantly different levels of expression in pairwise comparisons of parent and adapted clones. The extent of these changes points to the importance of mutations with regulatory and/or highly pleiotropic effects in the adaptive process. The four evolved clones all expressed fewer proteins than did the parent strain, supporting the hypothesis of energy conservation during evolutionary change. Forty-two proteins that could be assigned to known cellular functions were identified. The changes in some of them indicated that the evolved clones developed different adaptive mechanisms to glucose-limited environment. Changes were observed in the expression levels of proteins associated with translation, membrane composition, shock response, and active transport. A fraction of the changes could not be either explained or predicted from a consideration of the nature of the environment in which the clones evolved.
一个由单个克隆起始的大肠杆菌群体，在葡萄糖限制的连续培养中维持773代后，出现了广泛的形态和生理多态性。为了理解适应这种环境的机制，通过二维凝胶电泳检查了四个适应克隆和亲本菌株的总蛋白质模式。在亲本与适应克隆的成对比较中，约20%的蛋白质（绝对数量约为160种）显示出明显不同的表达水平。这些变化的程度表明在适应过程中具有调节和/或高度多效性效应的突变的重要性。四个进化克隆表达的蛋白质都比亲本菌株少，这支持了进化变化过程中能量守恒的假说。鉴定出了42种可归为已知细胞功能的蛋白质。其中一些蛋白质的变化表明，进化克隆对葡萄糖限制环境形成了不同的适应机制。在与翻译、膜组成、应激反应和主动运输相关的蛋白质表达水平上观察到了变化。从克隆进化所处环境的性质考虑，一部分变化无法得到解释或预测。
