Solution conformations of early intermediates in Mos1 transposition
Solution conformations of early intermediates in Mos1 transposition
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DOI：
10.1093/nar/gks1295
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发表时间：
2013-02-01
影响因子：
14.9
通讯作者：
Richardson, Julia M.
中科院分区：
文献类型：
--
作者：
Cuypers, Maxime G.;Trubitsyna, Maryia;Richardson, Julia M.
DNA转座酶通过剪切粘贴机制在基因组周围和基因组之间移动DNA转座子，从而促进基因组重排。DNA转座在一系列有序的核蛋白复合体中进行，这些复合体协调转座子末端的配对和裂解，以及新基因组位置裂解末端的整合。转座是通过转座酶识别标记每个转座子末端的反向重复序列来启动的。利用溶液散射和生化技术相结合的方法，我们测定了不含DNA的Mos1转座酶和与转座子末端结合的转座酶的溶液构象和化学计量比。我们证明了在没有DNA的情况下，Mos1转座酶是一个拉长的同源二聚体，并且N-末端55个残基包含第一个螺旋-转弯-螺旋基序，是二聚化所必需的。这种排列与Mos1配对末端复合体(PEC)中二聚体的紧凑、交叉结构显著不同。当转座酶结合到前切割复合体中的一个转座子末端时，转座酶保持拉长，并且DNA主要结合到一个转座酶单体上。我们认为，单端复合体中的构象变化，包括转座酶的一半旋转和第二个转座子末端的结合，可以促进PEC的组装。
DNA transposases facilitate genome rearrangements by moving DNA transposons around and between genomes by a cut-and-paste mechanism. DNA transposition proceeds in an ordered series of nucleoprotein complexes that coordinate pairing and cleavage of the transposon ends and integration of the cleaved ends at a new genomic site. Transposition is initiated by transposase recognition of the inverted repeat sequences marking each transposon end. Using a combination of solution scattering and biochemical techniques, we have determined the solution conformations and stoichiometries of DNA-free Mos1 transposase and of the transposase bound to a single transposon end. We show that Mos1 transposase is an elongated homodimer in the absence of DNA and that the N-terminal 55 residues, containing the first helix-turn-helix motif, are required for dimerization. This arrangement is remarkably different from the compact, crossed architecture of the dimer in the Mos1 paired-end complex (PEC). The transposase remains elongated when bound to a single-transposon end in a pre-cleavage complex, and the DNA is bound predominantly to one transposase monomer. We propose that a conformational change in the single-end complex, involving rotation of one half of the transposase along with binding of a second transposon end, could facilitate PEC assembly.