Sigma factor selectivity in Borrelia burgdorferi:: RpoS recognition of the ospE/ospF/elp promoters is dependent on the sequence of the-10 region
Sigma factor selectivity in Borrelia burgdorferi:: RpoS recognition of the ospE/ospF/elp promoters is dependent on the sequence of the-10 region
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DOI：
10.1111/j.1365-2958.2006.05066.x
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发表时间：
2006-03-01
影响因子：
3.6
通讯作者：
Radolf, JD
中科院分区：
文献类型：
--
作者：
Eggers, CH;Caimano, MJ;Radolf, JD
莱姆病病原体伯氏疏螺旋体的 ospE/ospF/elp 脂蛋白基因家族成员响应血液流入受感染蜱的中肠而转录上调。我们最近证明，尽管伯氏疏螺旋体菌株 297 的 ospF (P-ospF) 和 ospE (P-ospE) 基因的启动子之间具有高度相似性，但 ospF 的差异表达是 RpoS 依赖性的，而 ospE 则受 sigma(70) 控制。在此，我们使用伯氏疏螺旋体和大肠杆菌的野生型和 RpoS 缺陷菌株来分析由与 P-ospF、P-ospE 或两个混合启动子融合的绿色荧光蛋白 (gfp) 基因组成的转录报告基因，其中 P-ospF 和 P-ospE 的 -10 区域被转换 [P-ospF ((E - 10)) 和 P-ospE ((F - 10)) 分别]。我们发现 P-ospF-10 区域对于伯氏疏螺旋体中 RpoS 依赖性识别既是必要的也是充分的，而 P-ospE 的 sigma(70) 特异性取决于 -10 区域之外的元素。在大肠杆菌中，sigma 因子对这些启动子的选择性要宽松得多，每个启动子的表达主要是由于 sigma(70)。对伯氏疏螺旋体菌株 297 和 B31 的每个 ospE/ospF/elp 基因上游序列的比对表明，两个 B31 ospF 旁系同源物 [erpK (BBM38) 和 erpL (BBO39)] 具有与 P-ospF 几乎相同的 -10 区域。相应地，基于erpK和erpL启动子的gfp报告基因的表达是RpoS依赖性的。因此，P-ospF-10 区域的序列似乎可作为 RpoS 识别的基序，这是首次针对任何伯氏疏螺旋体启动子进行描述。总而言之，我们的数据支持这样的观点，即伯氏疏螺旋体利用 -10 区域的序列差异作为维持在蜱进食开始时激活的 RpoS 依赖和独立基因转录完整性的一种机制。
Members of the ospE/ospF/elp lipoprotein gene families of Borrelia burgdorferi, the Lyme disease agent, are transcriptionally upregulated in response to the influx of blood into the midgut of an infected tick. We recently have demonstrated that despite the high degree of similarity between the promoters of the ospF (P-ospF) and ospE (P-ospE) genes of B. burgdorferi strain 297, the differential expression of ospF is RpoS-dependent, while ospE is controlled by sigma(70). Herein we used wild-type and RpoS-deficient strains of B. burgdorferi and Escherichia coli to analyse transcriptional reporters consisting of a green fluorescent protein (gfp) gene fused to P-ospF, P-ospE, or two hybrid promoters in which the -10 regions of P-ospF and P-ospE were switched [P-ospF ((E - 10)) and P-ospE ((F - 10)) respectively]. We found that the P-ospF-10 region is both necessary and sufficient for RpoS-dependent recognition in B. burgdorferi, while sigma(70) specificity for P-ospE is dependent on elements outside of the -10 region. In E. coli, sigma factor selectivity for these promoters was much more permissive, with expression of each being primarily due to sigma(70). Alignment of the sequences upstream of each of the ospE/ospF/elp genes from B. burgdorferi strains 297 and B31 revealed that two B31 ospF paralogues [erpK (BBM38) and erpL (BBO39)] have -10 regions virtually identical to that of P-ospF. Correspondingly, expression of gfp reporters based on the erpK and erpL promoters was RpoS-dependent. Thus, the sequence of the P-ospF-10 region appears to serve as a motif for RpoS recognition, the first described for any B. burgdorferi promoter. Taken together, our data support the notion that B. burgdorferi utilizes sequence differences at the -10 region as one mechanism for maintaining the transcriptional integrity of RpoS-dependent and -independent genes activated at the onset of tick feeding.