Schonbrunn E, Eschenburg S, Luger K, Kabsch W, Amrhein N
Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO 80523, USA.
Proc Natl Acad Sci U S A. 2000 Jun 6;97(12):6345-9. doi: 10.1073/pnas.120120397.
The extrinsic fluorescence dye 8-anilino-1-naphthalene sulfonate (ANS) is widely used for probing conformational changes in proteins, yet no detailed structure of ANS bound to any protein has been reported so far. ANS has been successfully used to monitor the induced-fit mechanism of MurA [UDPGlcNAc enolpyruvyltransferase (EC )], an essential enzyme for bacterial cell wall biosynthesis. We have solved the crystal structure of the ANS small middle dotMurA complex at 1.7-A resolution. ANS binds at an originally solvent-exposed region near Pro-112 and induces a major restructuring of the loop Pro-112-Pro-121, such that a specific binding site emerges. The fluorescence probe is sandwiched between the strictly conserved residues Arg-91, Pro-112, and Gly-113. Substrate binding to MurA is accompanied by large movements especially of the loop and Arg-91, which explains why ANS is an excellent sensor of conformational changes during catalysis of this pharmaceutically important enzyme.
外在荧光染料8-苯胺基-1-萘磺酸盐（ANS）被广泛用于探测蛋白质的构象变化，但迄今为止尚未有与任何蛋白质结合的ANS的详细结构报道。ANS已成功用于监测MurA[UDPGlcNAc烯醇丙酮酸转移酶（EC ）]的诱导契合机制，MurA是细菌细胞壁生物合成的一种必需酶。我们已解析出分辨率为1.7埃的ANS·MurA复合物的晶体结构。ANS结合在靠近Pro-112的一个原本暴露于溶剂的区域，并诱导Pro-112-Pro-121环发生重大结构重组，从而形成一个特定的结合位点。荧光探针夹在严格保守的残基Arg-91、Pro-112和Gly-113之间。底物与MurA的结合伴随着特别是环和Arg-91的大幅移动，这解释了为什么ANS是这种具有药学重要性的酶催化过程中构象变化的优秀传感器。
