Université François Rabelais de Tours, GICC, CNRS, UMR 6239, UFR Sciences & Techniques, Parc Grandmont, 37200 Tours, France.
J Mol Biol. 2011 Jan 28;405(4):892-908. doi: 10.1016/j.jmb.2010.11.032. Epub 2010 Nov 24.
Transposases are proteins that have assumed the mobility of class II transposable elements. In order to map the interfaces involved in transposase-transposase interactions, we have taken advantage of 12 transposase mutants that impair mariner transposase-transposase interactions taking place during transposition. Our data indicate that transposase-transposase interactions regulating Mos1 transposition are sophisticated and result from (i) active MOS1 dimerization through the first HTH of the N-terminal domain, which leads to inverted terminal repeat (ITR) binding; (ii) inactive dimerization carried by part of the C-terminal domain, which prevents ITR binding; and (iii) oligomerization. Inactive dimers are nonpermissive in organizing complexes that produce ITR binding, but the interfaces (or interactions) supplied in this state could play a role in the various rearrangements needed during transposition. Oligomerization is probably not due to a specific MOS1 domain, but rather the result of nonspecific interactions resulting from incorrect folding of the protein. Our data also suggest that the MOS1 catalytic domain is a main actor in the overall organization of MOS1, thus playing a role in MOS1 oligomerization. Finally, we propose that MOS1 behaves as predicted by the pre-equilibrium existing model, whereby proteins are found to exist simultaneously in populations with diverse conformations, monomers and active and inactive dimers for MOS1. We were able to identify several MOS1 mutants that modify this pre-existing equilibrium. According to their properties, some of these mutants will be useful tools to break down the remaining gaps in our understanding of mariner transposition.
转座酶是具有类 II 转座元件迁移能力的蛋白质。为了绘制涉及转座酶-转座酶相互作用的界面，我们利用了 12 种转座酶突变体，这些突变体削弱了 mariner 转座酶-转座酶相互作用在转座过程中发生。我们的数据表明，调节 Mos1 转座的转座酶-转座酶相互作用是复杂的，并且源于 (i) 通过 N 端结构域的第一个 HTH 进行的活跃的 MOS1 二聚化，这导致反向末端重复 (ITR) 结合；(ii) 由 C 端结构域的一部分携带的无活性二聚化，这阻止了 ITR 结合；和 (iii) 寡聚化。无活性的二聚体在产生 ITR 结合的复合物的组织中是不可接受的，但在这种状态下提供的界面 (或相互作用) 可能在转座过程中所需的各种重排中发挥作用。寡聚化可能不是由于特定的 MOS1 结构域，而是由于蛋白质折叠不正确导致的非特异性相互作用的结果。我们的数据还表明，MOS1 催化结构域是 MOS1 整体组织的主要因素，因此在 MOS1 寡聚化中发挥作用。最后，我们提出 MOS1 行为与现有预平衡模型预测的一致，根据该模型，蛋白质同时存在于具有不同构象、单体和活性和无活性二聚体的种群中。我们能够鉴定出几种改变这种预先存在的平衡的 MOS1 突变体。根据它们的特性，其中一些突变体将成为打破我们对 mariner 转座理解的剩余差距的有用工具。
