Nöllmann Marcelo, He Jiuya, Byron Olwyn, Stark W Marshall
Division of Molecular Genetics, Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow G11 6NU, Scotland, United Kingdom.
Mol Cell. 2004 Oct 8;16(1):127-37. doi: 10.1016/j.molcel.2004.09.027.
Tn3 resolvase is a site-specific DNA recombinase, which catalyzes strand exchange in a synaptic complex containing twelve resolvase subunits and two res sites. Hyperactive mutants of resolvase can form a simpler complex (X synapse) containing a resolvase tetramer and two shorter DNA segments at which strand exchange takes place (site I). We have solved the low-resolution solution structure of the purified, catalytically competent X synapse from small-angle neutron and X-ray scattering data, using methods in which the data are fitted with models constructed by rigid body transformations of a published crystallographic structure of a resolvase dimer bound to site I. Our analysis reveals that the two site I fragments are on the outside of a resolvase tetramer core and provides some information on the quaternary structure of the tetramer. We discuss implications of our structure for the architecture of the natural synaptic complex and the mechanism of strand exchange.
Tn3 解离酶是一种位点特异性 DNA 重组酶，它在一个包含十二个解离酶亚基和两个 res 位点的突触复合体中催化链交换。解离酶的高活性突变体可形成一种更简单的复合体（X 突触），该复合体包含一个解离酶四聚体和两个较短的 DNA 片段，链交换发生在这些片段处（位点 I）。我们利用小角中子散射和 X 射线散射数据，通过将数据与由已发表的与位点 I 结合的解离酶二聚体晶体结构经刚体变换构建的模型进行拟合的方法，解析了纯化的、具有催化活性的 X 突触的低分辨率溶液结构。我们的分析表明，两个位点 I 片段位于解离酶四聚体核心的外部，并提供了一些关于四聚体四级结构的信息。我们讨论了我们的结构对天然突触复合体结构和链交换机制的影响。
