Alternate sigma factor RpoS is required for the in vivo-specific repression of Borrelia burgdorferi plasmid lp54-borne ospA and lp6.6 genes
Alternate sigma factor RpoS is required for the in vivo-specific repression of Borrelia burgdorferi plasmid lp54-borne ospA and lp6.6 genes
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DOI：
10.1128/jb.187.22.7845-7852.2005
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发表时间：
2005-11-01
影响因子：
3.2
通讯作者：
Radolf, JD
中科院分区：
文献类型：
--
作者：
Caimano, MJ;Eggers, CH;Radolf, JD
虽然在伯氏疏螺旋体的动物流行周期中已经对许多正调控基因座进行了特征描述，但对于在蜱吸血期间或在哺乳动物宿主体内抑制疏螺旋体基因座所涉及的机制知之甚少。在此，我们报道替代西格玛因子RpoS是至少两个依赖RpoD的伯氏疏螺旋体基因座ospA和lp6.6在体内特异性抑制所必需的。ospA和lp6.6的下调似乎需要一种其表达依赖于RpoS的阻遏分子，或者一种辅助因子，该辅助因子使RpoS能够直接与ospA和lp6.6启动子元件相互作用，从而阻断RpoD的转录。RpoS在宿主适应的最早阶段的核心作用表明，蜱吸血向螺旋体传递信号，触发对蜱到哺乳动物宿主转变至关重要的体内特异性毒力因子的RpoS依赖性抑制以及表达。
While numerous positively regulated loci have been characterized during the enzootic cycle of Borrelia burgdorferi, very little is known about the mechanism(s) involved in the repression of borrelial loci either during tick feeding or within the mammalian host. Here, we report that the alternative sigma factor RpoS is required for the in vivo-specific repression of at least two RpoD-dependent B. burgdorferi loci, ospA and lp6.6. The downregulation of ospA and Ip6.6 appears to require either a repressor molecule whose expression is RpoS dependent or an accessory factor which enables RpoS to directly interact with the ospA and Ip6.6 promoter elements, thereby blocking transcription by RpoD. The central role for RpoS during the earliest stages of host adaptation suggests that tick feeding imparts signals to spirochetes that trigger the RpoS-dependent repression, as well as expression, of in vivo-specific virulence factors critical for the tick-to-mammalian host transition.