Jardine Oliver, Gough Julian, Chothia Cyrus, Teichmann Sarah A
Department of Crystallography, Birkbeck College, London WC1E 7HX, United Kingdom.
Genome Res. 2002 Jun;12(6):916-29. doi: 10.1101/gr.228002.
The comparison of the small molecule metabolism pathways in Escherichia coli and Saccharomyces cerevisiae (yeast) shows that 271 enzymes are common to both organisms. These common enzymes involve 384 gene products in E. coli and 390 in yeast, which are between one half and two thirds of the gene products of small molecule metabolism in E. coli and yeast, respectively. The arrangement and family membership of the domains that form all or part of 374 E. coli sequences and 343 yeast sequences was determined. Of these, 70% consist entirely of homologous domains, and 20% have homologous domains linked to other domains that are unique to E. coli, yeast, or both. Over two thirds of the enzymes common to the two organisms have sequence identities between 30% and 50%. The remaining groups include 13 clear cases of nonorthologous displacement. Our calculations show that at most one half to two thirds of the gene products involved in small molecule metabolism are common to E. coli and yeast. We have shown that the common core of 271 enzymes has been largely conserved since the separation of prokaryotes and eukaryotes, including modifications for regulatory purposes, such as gene fusion and changes in the number of isozymes in one of the two organisms. Only one fifth of the common enzymes have nonhomologous domains between the two organisms. Around the common core very different extensions have been made to small molecule metabolism in the two organisms.
对大肠杆菌和酿酒酵母（酵母）中小分子代谢途径的比较表明，两种生物共有271种酶。这些共有酶在大肠杆菌中涉及384个基因产物，在酵母中涉及390个基因产物，分别占大肠杆菌和酵母中小分子代谢基因产物的二分之一到三分之二。确定了构成374个大肠杆菌序列和343个酵母序列全部或部分的结构域的排列和家族成员。其中，70%完全由同源结构域组成，20%具有与大肠杆菌、酵母或两者特有的其他结构域相连的同源结构域。两种生物共有的酶中，超过三分之二的序列同一性在30%至50%之间。其余的组包括13个明确的非直系同源替代案例。我们的计算表明，参与小分子代谢的基因产物中，最多只有二分之一到三分之二是大肠杆菌和酵母共有的。我们已经表明，自原核生物和真核生物分离以来，这271种酶的共同核心在很大程度上得到了保留，包括为调节目的而进行的修饰，如基因融合和两种生物之一中同工酶数量的变化。两种生物共有的酶中只有五分之一在结构域上是非同源的。围绕共同核心，两种生物对小分子代谢进行了非常不同的扩展。
