A unique fungal lysine biosynthesis enzyme shares a common ancestor with tricarboxylic acid cycle and leucine biosynthetic enzymes found in diverse organisms
A unique fungal lysine biosynthesis enzyme shares a common ancestor with tricarboxylic acid cycle and leucine biosynthetic enzymes found in diverse organisms
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DOI：
10.1007/pl00006319
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发表时间：
1998-04-01
影响因子：
3.9
通讯作者：
Bhattacharjee, JK
中科院分区：
文献类型：
--
作者：
Irvin, SD;Bhattacharjee, JK
真菌已经进化出一种独特的α-氨基己二酸赖氨酸生物合成途径。来自该途径的真菌特异性酶高乌头酸水合酶与来自不同分类组的乌头酸酶家族蛋白适度相似，所述分类组具有不同的获得赖氨酸的模式。我们已经使用的相似性高乌头酸水合酶异丙基苹果酸异构酶（亮氨酸生物合成），乌头酸酶（从三羧酸循环），铁响应元件结合蛋白（胞质乌头酸酶）从真菌和其他真核生物，真细菌和古细菌，以评估可能的进化方案的起源这一途径。精确的序列比对表明，乌头酸酶活性位点残基是高度保守的每一种酶，和插入序列位点是非常不同的。这种模式表明，强大的纯化选择起到了保护乌头酸酶活性位点残基的共同催化机制，许多其他的取代发生由于适应性进化或简单地缺乏功能的约束。我们假设，相似性是残留的祖先基因重复，这可能不会发生在真菌谱系，最大似然，邻居加入，最大简约系统发育比较表明，α-氨基己二酸途径酶是一个外群的所有顺乌头酸酶家族蛋白质的序列是目前可用的。
Fungi have evolved a unique alpha-aminoadipate pathway for lysine biosynthesis. The fungal-specific enzyme homoaconitate hydratase from this pathway is moderately similar to the aconitase-family proteins from a diverse array of taxonomic groups, which have varying modes of obtaining lysine. We have used the similarity of homoaconitate hydratase to isopropylmalate isomerase (serving in leucine biosynthesis), aconitase (from the tricarboxylic acid cycle), and iron-responsive element binding proteins (cytosolic aconitase) from fungi and other eukaryotes, eubacteria, and archaea to evaluate possible evolutionary scenarios for the origin of this pathway. Refined sequence alignments show that aconitase active site residues are highly conserved in each of the enzymes, and intervening sequence sites are quite dissimilar. This pattern suggests strong purifying selection has acted to preserve the aconitase active site residues for a common catalytic mechanism; numerous other substitutions occur due to adaptive evolution or simply lack of functional constraint. We hypothesize that the similarities are the remnants of an ancestral gene duplication, which may not have occurred within the fungal lineage, Maximum likelihood, neighbor joining, and maximum parsimony phylogenetic comparisons show that the alpha-aminoadipate pathway enzyme is an outgroup to all aconitase family proteins for which sequence is currently available.