Solution structure and functional ligand screening of HI0719, a highly conserved protein from bacteria to humans in the YjgF/YER057c/UK114 family.
Solution structure and functional ligand screening of HI0719, a highly conserved protein from bacteria to humans in the YjgF/YER057c/UK114 family.
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DOI：
10.1021/bi020541w
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发表时间：
2003-01
期刊：
影响因子：
2.9
通讯作者：
L. Parsons;N. Bonander;E. Eisenstein;M. Gilson;V. Kairys;J. Orban
中科院分区：
文献类型：
--
作者：
L. Parsons;N. Bonander;E. Eisenstein;M. Gilson;V. Kairys;J. Orban
HI0719属于一个高度保守的蛋白质大家族，没有确定的分子功能，存在于从细菌到人类的各种生物中。我们描述了HI0719的核磁共振结构，这是该家族成员的第一个溶液结构。整个折叠结构与枯草芽孢杆菌YabJ和大肠杆菌YjgF两个同源物的晶体结构相似，虽然序列同源性很低，没有明显的功能联系，但这三个结构都与分支酸变位酶相似。HI0719是一种均三聚体，在亚基界面上有一个明显的空腔。蛋白质高同一性基团中的七个不变残基中有六个位于这个空腔中，这表明这可能是小分子的结合部位。以之前发表的关于HI0719家族成员生物学作用的观察为指导，利用核磁共振光谱筛选了100多个自然产生的小分子或结构类似物的配体结合。靶向筛选方法确定了6个化合物，它们与HI0719在假定的活性部位结合。这些化合物中有五个是α-酮酸或α，β-不饱和酸，而第六个化合物的结构相似。以前的研究已经提出，一些HI0719同系物可能作用于异亮氨酸生物合成途径中的小分子，如果这是正确的，这里给出的配体筛选结果表明，这种作用很可能发生在2-酮丁酸酯和/或其不稳定的烯胺前体上。
HI0719 belongs to a large family of highly conserved proteins with no definitive molecular function and is found in organisms ranging from bacteria to humans. We describe the NMR structure of HI0719, the first solution structure for a member of this family. The overall fold is similar to the crystal structures of two homologues, YabJ from Bacillus subtilis and YjgF from Escherichia coli, and all three structures are similar to that of chorismate mutase, although there is little sequence homology and no apparent functional connection. HI0719 is a homotrimer with a distinct cavity located at the subunit interface. Six of the seven invariant residues in the high identity group of proteins are located in this cavity, suggesting that this may be a binding site for small molecules. Using previously published observations about the biological role of HI0719 family members as a guide, over 100 naturally occurring small molecules or structural analogues were screened for ligand binding using NMR spectroscopy. The targeted screening approach identified six compounds that bind to HI0719 at the putative active site. Five of these compounds are either alpha-keto acids or alpha,beta-unsaturated acids, while the sixth compound is structurally similar. Previous studies have proposed that some HI0719 homologues may act on small molecules in the isoleucine biosynthetic path and, if this is correct, the ligand screening results presented here suggest that the interaction most likely occurs with 2-ketobutyrate and/or its unstable enamine precursor.