Tiny enzyme uses context to succeed

摘要

内在膜酶“甘油二酯激酶”参与革兰氏阴性细rn菌中“来自周质膜的寡糖”和外膜脂多糖的合rn成。仅含有121个氨基酸残基，这种酶是已知rn最小的激酶，它已成为膜蛋白行为研究及酶学rn研究的一个模型。%The bacterial enzyme diacylglycerol kinase has always been a bit of a rebel. As an apparent evolutionary 'orphan', this integral membrane protein is functionally and structurally distinct from other kinases identified so far. Furthermore, its size (just 121 amino-acid residues) makes its modus operandi challenging to understand: how does so small an enzyme manage to span the cell membrane while still forming a functional active site that must accommodate not only a bulky, fatty substrate but also a water-soluble ATP molecule? On page 521 of this issue, Li et al. report crystal structures of diacylglycerol kinase from the bacterium Escherichia coli. The structures reveal how the enzyme exploits the milieu in which it resides, greatly increasing our understanding of this protein and providing insight into integral membrane enzymes in general.