Sequence and expression analysis of the ompA gene of Rickettsia peacockii, an endosymbiont of the rocky mountain wood tick, Dermacentor andersoni
Sequence and expression analysis of the ompA gene of Rickettsia peacockii, an endosymbiont of the rocky mountain wood tick, Dermacentor andersoni
复制标题
DOI：
10.1128/aem.70.11.6628-6636.2004
复制
发表时间：
2004-11-01
影响因子：
4.4
通讯作者：
Munderloh, UG
中科院分区：
文献类型：
--
作者：
Baldridge, GD;Burkhardt, NY;Munderloh, UG
蒙大拿州落基山斑点热病的传播动态似乎受到孔雀立克次体的调节，孔雀立克次体是一种硬质共生立克次体，干扰了强毒立克次体的传播。为了阐明两种立克次体之间的分子关系，并为如何利用这种干扰现象收集信息，我们研究了一个主要的立克次体外膜蛋白基因OmpA，该基因被认为与斑点热群立克次体(SFGR)的感染和发病有关，但在共生体中没有表达。基于对SFGR OmpA基因的PCR扩增和DNA序列分析，我们证明了孔雀立克次体与里氏立克次体的亲缘关系最近。我们发现，最初被描述为来自蒙大拿州比特罗特山谷东侧的安德森革螨东侧媒介的孔雀杆菌，仍然存在于该人群中以及在科罗拉多州两个相距甚远的地点收集的安德森革虱中。孔雀立克次体OmpA基因具有与立克次体OmpA相同的三个相同的提前终止密码子和一个弱化的核糖体结合位点共同序列。孔雀杆菌OmpA启动子与立克次氏杆菌的启动子非常相似，根据逆转录-聚合酶链式反应结果，该启动子具有功能。十二烷基硫酸钠-聚丙烯酰胺凝胶电泳法和Western blotting结果表明，孔雀立克次体感染体外培养的硬蜱细胞中未检测到OmpA翻译产物。双重免疫标记研究表明，在感染立克次体HLP#2株的硬蜱细胞中，肌动蛋白尾部结构，而在感染孔雀杆菌的细胞中不存在。
The transmission dynamics of Rocky Mountain spotted fever in Montana appears to be regulated by Rickettsia peacockii, a tick symbiotic rickettsia that interferes with transmission of virulent Rickettsia rickeusii. To elucidate the molecular relationships between the two rickettsiae and glean information on how to possibly exploit this interference phenomenon, we studied a major rickettsial outer membrane protein gene, ompA, presumed to be involved in infection and pathogenesis of spotted fever group rickettsiae (SFGR) but which is not expressed in the symbiont. Based on PCR amplification and DNA sequence analysis of the SFGR ompA gene, we demonstrate that R. peacockii is the most closely related of all known SFGR to R. rickettsii. We show that R. peacockii, originally described as East Side agent in Dermacentor andersoni ticks from the east side of the Bitterroot Valley in Montana, is still present in that tick population as well as in D. andersoni ticks collected at two widely separated locations in Colorado. The ompA genes of R. peacockii from these locations share three identical premature stop codons and a weakened ribosome binding site consensus sequence relative to ompA of R. rickettsii. The R. peacockii ompA promoter closely resembles that of R. rickettsii and is functional based on reverse transcription-PCR results. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blotting showed that OmpA translation products were not detected in cultured tick cells infected with R. peacockii. Double immunolabeling studies revealed actin tail structures in tick cells infected with R. rickettsii strain Hlp#2 but not in cells infected with R. peacockii.