EVOLUTION OF STRUCTURE AND FUNCTION IN O-SUCCINYLBENZOATE SYNTHASE

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 了解蛋白质如何进化以提供精致的特异性和熟练的活性是生物学中的一个基本问题，对蛋白质功能预测和蛋白质工程具有重要意义。为了研究这一问题，我们分析了邻丁二酸苯甲酸合成酶/N-酰基氨基酸消旋酶(OSBS/NAAR)家族的结构和功能的进化，该家族是具有不同机制的烯醇化酶超家族的一部分。虽然这个家族的所有特征成员都催化了OSBS反应，但这个家族是非常不同的，一些成员有15%的同一性。此外，该家族的一个成员，Amycolatopsis OSBS/NAAR，是混杂的，既催化脱水又催化外消旋。虽然OSBS/NAAR家族似乎具有单一的进化起源，但没有发现该家族特有的序列或结构基序；该家族中保守的所有残基也存在于具有不同功能的烯醇化酶超家族成员中。根据它们的种类分布，几个类似于Amycolatopsis OSBS/NAAR的未知蛋白似乎是通过侧向基因转移传递的。与Amycolatopsis OSBS/NAAR一样，它们可能具有OSBS的额外或替代功能，因为许多来自缺乏OSBS作为中间体的途径的生物体。除了功能上的差异，OSBS/NAAR家族还表现出令人惊讶的结构变化，包括两个结构域之间的巨大取向差异。这些结果为蛋白质进化提供了几点见解。首先，同源蛋白可以表现出显著的结构变化，而且特异性可以保持不变，几乎不需要保存与配体接触的残基。其次，一组与Amycolatopsis OSBS/NAAR相似的蛋白质的发现支持了这样一种假说，即新的蛋白质功能是通过混杂的中间体进化的。最后，进化、结构和序列分析的组合确定了可能启动蛋白质的特征，如amyc。 Olatopsis OSBS/NAAR，用于进化新的活动。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Understanding how proteins evolve to provide both exquisite specificity and proficient activity is a fundamental problem in biology that has implications for protein function prediction and protein engineering. To study this problem, we analyzed the evolution of structure and function in the o-succinylbenzoate synthase/N-acylamino acid racemase (OSBS/NAAAR) family, part of the mechanistically diverse enolase superfamily. Although all characterized members of the family catalyze the OSBS reaction, this family is extraordinarily divergent, with some members sharing <15% identity. In addition, a member of this family, Amycolatopsis OSBS/NAAAR, is promiscuous, catalyzing both dehydration and racemization. Although the OSBS/NAAAR family appears to have a single evolutionary origin, no sequence or structural motifs unique to this family could be identified; all residues conserved in the family are also found in enolase superfamily members that have different functions. Based on their species distribution, several uncharacterized proteins similar to Amycolatopsis OSBS/NAAAR appear to have been transmitted by lateral gene transfer. Like Amycolatopsis OSBS/NAAAR, these might have additional or alternative functions to OSBS because many are from organisms lacking the pathway in which OSBS is an intermediate. In addition to functional differences, the OSBS/NAAAR family exhibits surprising structural variations, including large differences in orientation between the two domains. These results offer several insights into protein evolution. First, orthologous proteins can exhibit significant structural variation, and specificity can be maintained with little conservation of ligand-contacting residues. Second, the discovery of a set of proteins similar to Amycolatopsis OSBS/NAAAR supports the hypothesis that new protein functions evolve through promiscuous intermediates. Finally, a combination of evolutionary, structural, and sequence analyses identified characteristics that might prime proteins, such as Amyc olatopsis OSBS/NAAAR, for the evolution of new activities.