Molecular Mechanisms of msp2 Variation in Rickettsiae

超出所提供的空间。本建议的目的是提高我们对引起人类和动物埃利希体病和无形体病的蜱传立克次体病原体发病机制的理解。这些病原体有效地利用一个小基因组（<1.5 Mb）来逃避免疫反应，并在哺乳动物宿主中建立持续感染，在蜱的中肠和唾液腺中定植和复制，并在蜱的重新进食后发展感染性，从而实现传播。MSP2最初是在边缘无原体中发现的，牛和蜱感染这种病原体为发现用于修饰表面蛋白质组的机制提供了一个很好的模型。在之前的项目期间，我们确定了MSP2的单个表达位点的片段基因转换，以及相关的表面平行MSP3，作为产生表面多样性的主要机制，并证明了哺乳动物宿主和蜱虫载体之间操纵子编码蛋白的差异表达。在人类患者中，嗜吞噬细胞无原体也使用类似的基因转换机制来表达大量外膜蛋白，其他研究也支持多位点表达以产生表面多样性。对边角拟南芥基因组的分析揭示了一个与msp2相关的外膜蛋白复杂家族。该msp2超家族由32个旁系物组成，包括两个msp2和msp3操纵子连接的表达位点、一个msp4基因位点、多个msp2和msp3假基因以及其他未表征的msp2-1样旁系物。我们假设这些同源物的差异表达和它们之间的重组产生了病原体表面的多样性，并提供了生物体适应和持续在不同宿主和细胞环境中的能力。本提案的具体目的是：1]确定msp2超家族基因在哺乳动物和无脊椎动物宿主感染期间是否存在差异表达；2]确定msp2超家族基因簇内的操纵子结构和多样性的产生；3]确定msp2超家族蛋白在哺乳动物和无脊椎动物宿主中的差异调控机制；[4]比较msp2超家族蛋白在边缘芽孢杆菌和嗜吞噬细胞芽孢杆菌中的表达调控。网站性能 ======================================== 节结束 ===========================================

EXCEED THE SPACE PROVIDED. The objective of this proposal is to improve our understanding of the mechanisms of pathogenesis of tick- borne rickettsial pathogens that cause ehrlichiosis and anaplasmosis of humans and animals. These pathogens efficiently utilize a small genome (<1.5 Mb) to evade the immune response and establish persistent infection in the mammalian reservoir host, to colonize and replicate in the tick midgut and salivary glands, and to develop infectivity upon renewed feeding of the tick to effect onward transmission. MSP2 was initially defined in Anaplasma marginale and infections of cattle and ticks with this pathogen provide an excellent model for discovering the mechanisms used to modify the surface proteome. In the prior project period, we identified segmental gene conversion of single expression sites for MSP2, and a related surface paralogue MSP3, as a primary mechanism for generating surface diversity and demonstrated differential expression of operon-encoded proteins between the mammalian host and tick vector. A similar gene conversion mechanism is used by Anaplasma phagocytophilum to express a large repertoire of outer membrane proteins in human patients and studies by others support expression from multiple loci to generate surface diversity. Analysis of the A. marginale genome reveals a complex family of outer membrane protein genes related to msp2. This msp2 superfamily is comprised of 32 paralogues, comprising the two msp2 and msp3 operon-linked expression sites, a single msp4 gene locus, multiple msp2 and msp3 pseudogenes, and other uncharacterized msp2-1ike paralogues. We hypothesize that differential expression of these paralogues and recombination between them generates diversity in the pathogen surface and provides the ability of organisms to adapt to and persist in different hosts and cellular environments. The specific aims of the present proposal are: 1] Determine if msp2 superfamily genes are differentially expressed during infection of the mammalian and invertebrate hosts; 2] Determine the operon structure and generation of diversity within msp2 superfamily gene clusters; 3] Identify the mechanisms for differential regulation of the msp2 superfamily proteins in the mammalian and invertebrate hosts; and 4] Compare regulation of expression of msp2 superfamily proteins in A. marginale and A. phagocytophilum. PERFORMANCE SITE ========================================Section End===========================================