Wardle Simon J, O'Carroll Michelle, Derbyshire Keith M, Haniford David B
Department of Biochemistry, University of Western Ontario, London, Ontario N6A 5C1 Canada.
Genes Dev. 2005 Sep 15;19(18):2224-35. doi: 10.1101/gad.1338905.
The histone-like nucleoid structuring (H-NS) protein is a global transcriptional regulator that is known to regulate stress response pathways and virulence genes in bacteria. It has also been implicated in the regulation of bacterial transposition systems, including Tn10. We demonstrate here that H-NS promotes Tn10 transposition by binding directly to the transposition complex (or transpososome). We present evidence that, upon binding, H-NS induces the unfolding of the Tn10 transpososome and helps to maintain the transpososome in an unfolded state. This ensures that intermolecular (as opposed to self-destructive intramolecular) transposition events are favored. We present evidence that H-NS binding to the flanking donor DNA of the transpososome is the initiating event in the unfolding process. We propose that by recruiting H-NS as a modulator of transposition, Tn10 has evolved a means of sensing changes in host physiology, as the amount of H-NS in the cell, as well its activity, are responsive to changes in environmental conditions. Sensing of environmental changes through H-NS would allow transposition to occur when it is most opportune for both the transposon and the host.
类组蛋白核仁结构蛋白（H-NS）是一种全局性转录调节因子，已知其可调节细菌中的应激反应途径和毒力基因。它还与细菌转座系统（包括Tn10）的调节有关。我们在此证明，H-NS通过直接结合转座复合物（或转座体）来促进Tn10转座。我们提供的证据表明，结合后，H-NS会诱导Tn10转座体展开，并有助于将转座体维持在展开状态。这确保了分子间（而非自我破坏的分子内）转座事件占优势。我们提供的证据表明，H-NS与转座体侧翼供体DNA的结合是展开过程中的起始事件。我们提出，通过招募H-NS作为转座的调节剂，Tn10已经进化出一种感知宿主生理变化的方式，因为细胞中H-NS的量及其活性会对环境条件的变化做出反应。通过H-NS感知环境变化将使转座在对转座子和宿主最有利的时机发生。
