Identification of functional promoters in the msp2 expression loci of Anaplasma marginale and Anaplasma phagocytophilum
Identification of functional promoters in the msp2 expression loci of Anaplasma marginale and Anaplasma phagocytophilum
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DOI：
10.1016/j.gene.2005.03.036
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发表时间：
2005-06-20
期刊：
影响因子：
3.5
通讯作者：
Palmer, GH
中科院分区：
文献类型：
--
作者：
Barbet, AF;Agnes, JT;Palmer, GH
无形体科中的生物体是世界范围内重要的蜱传病原体，并导致最近出现的人类感染。尽管它们在医学上很重要，但人们对这些生物如何调节哺乳动物宿主、蜱虫载体或宿主与载体之间的转换过程中的基因表达知之甚少。然而，很明显，除了重组机制之外，基因调控对于这些小基因组病原体适应明显不同的环境至关重要。在这项研究中，我们确定并建立三个启动子元件的功能，在基因座编码的主要外膜蛋白表达位点的边缘无形体和嗜吞噬细胞无形体。该基因座的基因表达涉及经典和非典型多顺反子转录本。所鉴定的启动子元件具有与大肠杆菌中定义的结构相似的结构，并且在原核无细胞转录和翻译系统中以及在重组大肠杆菌中驱动蛋白质表达中具有功能。杆菌两个最强的启动子在体外和重组E。coli中也显示出在A.边缘感染的细胞，如通过下游转录物的定量所确定的。启动子在A. marginale和A.结果表明，嗜吞噬细胞菌的两个基因座具有相似的结构和活性，支持这两个基因座是同线性的，具有功能保守性。此外，它们在启动子内共享结构元件，这些结构元件似乎是可能的调控位点。这些数据增强了我们对这些可变外膜蛋白的表达如何在蜱传传播和感染的关键阶段受到控制的理解。(c)2005 Elsevier B.V.保留所有权利。
Organisms in the family Anaplasmataceae are important tick-borne pathogens of livestock worldwide and cause recently emergent infections in humans. Despite their medical importance, very little is known about how these organisms regulate gene expression in the mammalian host, the tick vector, or during transition between the host and vector. However, it is clear that gene regulation, in addition to recombinatorial mechanisms, is essential for these small genome pathogens to adapt to distinctly different environments. In this study, we identify and establish the function of three promoter elements in the locus encoding major outer membrane protein expression sites in both Anaplasma marginale and Anaplasma phagocytophilum. Gene expression from this locus involves both classical and atypical polycistronic transcripts. The identified promoter elements have a structure similar to that defined in Escherichia coli and are functional in driving protein expression in a prokaryotic cell-free transcription and translation system and in recombinant E. coli. The two strongest promoters identified in vitro and with recombinant E. coli were also shown to be functional in A. marginale infected cells, as determined by quantification of downstream transcripts. The promoters in both A. marginale and A. phagocytophilum have similar structure and activity, supporting the conclusion that the two loci are syntenic with conservation of function. In addition, they share structural elements within the promoters that appear to be likely sites for regulation. These data enhance our understanding of how expression of these variable outer membrane proteins may be controlled in the key stages of tick-borne transmission and infection. (c) 2005 Elsevier B.V. All rights reserved.