Structure and function of novel prokaryotic DNA transposases

我们最近开始了对多重耐药细菌插入序列移动的研究，重点是产生碳青霉烯酶的肠杆菌(CPE)。转座因子通常与抗生素耐药决定因素有关，这表明在耐药的出现中发挥了作用。据报道，一个插入序列IS26经常与抗性决定因素相关，但其作用尚不清楚。我们已经分析了来自NIH临床中心的几个临床和监测CPE分离株的70个IS26拷贝的基因组背景。我们以靶点复制(TSD)及其分布模式为指导，发现很大一部分质粒重组是由IS26分子内复制换位引起的，包括复制子融合、DNA倒置和缺失。我们现在已经将这些研究扩展到其他类型的移动元件。我们还感兴趣的是，从其活跃的移动元件的角度来看，携带多药耐药决定因素的质粒正在进行重组。 最近，甚至在肠杆菌科中也观察到了对粘菌素的抗药性，粘菌素是一种“最后的”抗生素。我们发现粘菌素抗性基因的传播似乎与特定的移动遗传元件有关，我们正在对其进行表征。 一种在多重抗生素耐药中起核心作用的原核生物转座机制是所谓的复制-输出-粘贴-插入机制。尽管这一过程至关重要，但目前还没有关于这一过程如何运作的机械性信息。最近，我们发现了一种名为IS256的可移动遗传元件，它使用了这一过程，并且我们已经能够产生IS256家族转座酶的晶体，它与DNA络合在一起，很好地衍射了X射线。晶体结构测定正在进行中。 科西奥，M.J.和德比郡，K.M.(2003)NAT.莫尔牧师。牢房。比奥尔。4865-877。 Debets-Ossenkopp，Y.J.等人。(1999)抗菌剂。化学其他探员。43,2657-2662。 Sebai hia，M.等人。(2006)《自然》杂志。38,779-786。

We have recently initiated an investigation of Insertion Sequence movements in multi drug resistant bacteria with a focus on carbapenemase-producing Enterobacteriacaea (CPE). Transposable elements are often associated with antibiotic resistance determinants, suggesting a role in the emergence of resistance. One insertion sequence, IS26, has been reported to be frequently associated with resistance determinants, but its role remained unclear. We have analyzed the genomic contexts of 70 IS26 copies in several clinical and surveillance CPE isolates from the NIH Clinical Center. We used target site duplications (TSDs) and their distribution patterns as guides and discovered that a large fraction of plasmid reorganizations result from IS26 intramolecular replicative transpositions, including replicon fusions, DNA inversions, and deletions. We have now extended these studies to other types of mobile elements. We are also interested in following the ongoing reorganization of plasmids carrying multidrug-resistant determinants from the perspective of their active mobile elements. More recently,resistance even for colistin, which is a "last resort" antibiotics have been observed to emerge in enterobacteriaceae. We have discovered that dissemination of the colistin resistance gene appears linked to a particular mobile genetic element, and we are in the process of its characterization. One prokaryotic transposition mechanism that clearly plays a central role in the emergence of multi antibiotic resistance is the so-call copy-out-paste-in mechanism. Despite its central importance, there is no current mechanistic information available regarding how this process works. Recently, we have identified a mobile genetic element called IS256 that uses this process and we have been able to generate crystals of the IS256 family transposase complexed with DNA that diffracts X-rays well. Crystallographic structure determination is underway. Curcio, M.J. and Derbyshire, K.M. (2003) Nat. Rev. Mol. Cell. Biol. 4, 865-877. Debets-Ossenkopp, Y.J., et al. (1999) Antimicrob. Agents Chemother. 43, 2657-2662. Sebaihia, M. et al. (2006) Nature Genet. 38, 779-786.