Evidence of selection for low cognate amino acid bias in amino acid biosynthetic enzymes
Evidence of selection for low cognate amino acid bias in amino acid biosynthetic enzymes
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DOI：
10.1111/j.1365-2958.2005.04566.x
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发表时间：
2005-05-01
影响因子：
3.6
通讯作者：
Savageau, MA
中科院分区：
文献类型：
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作者：
Alves, R;Savageau, MA
如果负责给定氨基酸生物合成的酶受到抑制并且同源氨基酸库突然耗尽，那么如果这些酶主要由同源氨基酸组成，那么这些酶的去抑制和库的补充将会出现问题。氨基酸。在众所周知的“第二十二条军规”中，细胞将缺乏制造氨基酸所必需的酶，并且它们也将缺乏制造所需酶所必需的氨基酸。基于这种情况，我们假设进化将导致选择同源氨基酸含量相对较低的氨基酸生物合成酶。我们称之为“同源偏差假设”。在这里，我们直接使用大肠杆菌蛋白质组的数据来测试该假设的几个含义。多项证据表明，20 种氨基酸生物合成途径中有 15 种存在明显的低同源偏倚。与密切相关的鼠伤寒沙门氏菌的比较显示出相似的结果。与关系较远的枯草芽孢杆菌的比较显示出总体相似性以及同源偏差的详细特征的显着差异。因此，低同源偏差的选择在塑造一大类细胞蛋白质的氨基酸组成方面起着重要作用。
If the enzymes responsible for biosynthesis of a given amino acid are repressed and the cognate amino acid pool suddenly depleted, then derepression of these enzymes and replenishment of the pool would be problematic, if the enzymes were largely composed of the cognate. amino acid. In the proverbial 'Catch 22', cells would lack the necessary enzymes to make the amino acid, and they would lack the necessary amino acid to make the needed enzymes. Based on this scenario, we hypothesize that evolution would lead to the selection of amino acid biosynthetic enzymes that have a relatively low content of their cognate amino acid. We call this the 'cognate bias hypothesis'. Here we test several implications of this hypothesis directly using data from the proteome of Escherichia coli. Several lines of evidence show that low cognate bias is evident in 15 of the 20 amino acid biosynthetic pathways. Comparison with closely related Salmonella typhimurium shows similar results. Comparison with more distantly related Bacillus subtilis shows general similarities as well as significant differences in the detailed profiles of cognate bias. Thus, selection for low cognate bias plays a significant role in shaping the amino acid composition for a large class of cellular proteins.