Cis-acting DNA elements flanking the variable major protein expression site of Borrelia hermsii are required for murine persistence.
Cis-acting DNA elements flanking the variable major protein expression site of Borrelia hermsii are required for murine persistence.
复制标题
赫氏疏螺旋体可变主要蛋白表达位点侧翼的顺式作用 DNA 元件是小鼠持久性所必需的。
DOI：
10.1002/mbo3.569
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发表时间：
2018
期刊：
影响因子：
3.4
通讯作者：
Bankhead,Troy
中科院分区：
文献类型：
--
作者：
James,AllisonE;Rogovskyy,ArtemS;Crowley,MichaelA;Bankhead,Troy
在赫氏疏螺旋体中，抗原变异是非互惠基因转换事件的结果，该事件将~60个沉默的可变主要蛋白基因中的一个置于单个转录活性启动子的下游。上游同源序列(UHS)和下游同源序列(DHS)是两个公认的DNA元件，它们被预测为同源重组的交叉点。在这篇报道中，使用了一种定向缺失/插入顺式互补技术来直接评估这些元件在抗原转换中的作用。结果表明，表达位点的缺失导致病原体在免疫活性小鼠中无法复发，所利用的技术成功地产生了能够进行抗原转换的互补突变体。随后又产生了表达基因UHS和DHS突变的额外互补克隆，并评估了它们在具有免疫能力的小鼠身上复发的能力。UHS的突变和DHS内的反向重复序列使这些突变体无法复发。总体而言，这些结果建立了DHS反向重复对抗原切换的要求，并支持了UHS Forb在哺乳动物宿主中持续存在的重要性。
InBorrelia hermsii, antigenic variation occurs as a result of a nonreciprocal gene conversion event that places one of ~60 silent variable major protein genes downstream of a single, transcriptionally active promoter. The upstream homology sequence (UHS) and downstream homology sequence (DHS) are two putativecis‐acting DNA elements that have been predicted to serve as crossover points for homologous recombination. In this report, a targeted deletion/in ciscomplementation technique was used to directly evaluate the role for these elements in antigenic switching. The results demonstrate that deletion of the expression site results in an inability of the pathogen to relapse in immunocompetent mice, and that the utilized technique was successful in producing complemented mutants that are capable of antigenic switching. Additional complemented clones with mutations in the UHS and DHS of the expressed locus were then generated and evaluated for their ability to relapse in immunocompetent mice. Mutation of the UHS and inverted repeat sequence within the DHS rendered these mutants incapable of relapsing. Overall, the results establish the requirement of the inverted repeat of the DHS for antigenic switching, and support the importance of the UHS forB. hermsiipersistence in the mammalian host.