Subramanya H S, Bird L E, Brannigan J A, Wigley D B
Laboratory of Molecular Biophysics, University of Oxford, UK.
Nature. 1996 Nov 28;384(6607):379-83. doi: 10.1038/384379a0.
There are a wide variety of helicases that unwind helical DNA and RNA substrates. The twelve helicases that have been identified in Escherichia coli play a role in almost all cellular processes involving nucleic acids. We have solved the crystal structure of a monomeric form of a DNA helicase from Bacillus stearothermophilus, alone and in a complex with ADP, at 2.5 and 2.9 A resolution, respectively. The enzyme comprises two domains with a deep cleft running between them. The ATP-binding site, which is situated at the bottom of this cleft, is formed by motifs that are conserved across the superfamily of related helicases. Unexpected structural homology with the DNA recombination protein, RecA, suggests how ATP binding and hydrolysis may drive conformational changes of the enzyme during catalysis, and implies that there is a common mechanism for all helicases.
有各种各样的解旋酶可解开螺旋状的DNA和RNA底物。在大肠杆菌中已鉴定出的十二种解旋酶几乎参与了所有涉及核酸的细胞过程。我们分别以2.5埃和2.9埃的分辨率解析了嗜热脂肪芽孢杆菌DNA解旋酶单体形式单独存在以及与ADP形成复合物时的晶体结构。该酶由两个结构域组成，它们之间有一条深裂缝。位于这条裂缝底部的ATP结合位点由相关解旋酶超家族中保守的基序形成。与DNA重组蛋白RecA意外的结构同源性表明了ATP结合和水解在催化过程中如何驱动酶的构象变化，并暗示所有解旋酶存在共同的机制。
