Keck Structural Biology Laboratory, Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724, USA.
Genes Dev. 2012 Feb 1;26(3):294-303. doi: 10.1101/gad.182691.111.
A wealth of genetic information and some biochemical analysis have made the GAL regulon of the yeast Saccharomyces cerevisiae a classic model system for studying transcriptional activation in eukaryotes. Galactose induces this transcriptional switch, which is regulated by three proteins: the transcriptional activator Gal4p, bound to DNA; the repressor Gal80p; and the transducer Gal3p. We showed previously that NADP appears to act as a trigger to kick the repressor off the activator. Sustained activation involves a complex of the transducer Gal3p and Gal80p mediated by galactose and ATP. We solved the crystal structure of the complex of Gal3p-Gal80p with α-D-galactose and ATP to 2.1 Å resolution. The interaction between the proteins occurs only when Gal3p is in a "closed" state induced by ligand binding. The structure of the complex provides a rationale for the phenotypes of several well-known Gal80p and Gal3p mutants as well as the lack of galactokinase activity of Gal3p.
丰富的遗传信息和一些生化分析使酵母 Saccharomyces cerevisiae 的 GAL 调控系统成为研究真核生物转录激活的经典模式系统。半乳糖诱导这种转录开关，由三种蛋白质调节：与 DNA 结合的转录激活因子 Gal4p、抑制因子 Gal80p 和传感器 Gal3p。我们之前表明，NADP 似乎充当触发器，将抑制剂从激活剂上脱离。持续的激活涉及到传感器 Gal3p 和 Gal80p 的复合物，由半乳糖和 ATP 介导。我们解决了 Gal3p-Gal80p 与 α-D-半乳糖和 ATP 的复合物的晶体结构，分辨率为 2.1 Å。只有当 Gal3p 处于配体结合诱导的“关闭”状态时，蛋白质之间才会发生相互作用。该复合物的结构为几种众所周知的 Gal80p 和 Gal3p 突变体的表型以及 Gal3p 缺乏半乳糖激酶活性提供了合理的解释。
