Structural basis of TLR and NLR recognition and signaling

描述（由申请人提供）：先天免疫提供了针对病原体或病原体相关分子模式的第一道防线。在已知的先天性受体中，Toll样受体（TLR）和NOD样受体（NLR）共有共同的结构基序，其由多个富含亮氨酸的重复序列（LRR）组成，每个重复序列的氨基酸残基和长度具有一些变异性。无颌鱼可变淋巴细胞受体（VLRs）的LRR结构研究也表明，LRR结构域在配体识别中很重要。因此，TLR和NLR的LRR对于与激动剂配体的相互作用是必需的，以便在先天免疫中启动细胞信号传导。此外，当LRR结构域从信号传导结构域脱离时，它可以通过竞争性结合配体来负调节先天免疫。因此，本研究的最终目标是促进对TLR和NLR中LRR在配体诱导的激活和信号传导中的结构和功能的理解。TLR 1/2/3/4/5/6中LRR结构域的结构和生物物理学表征已经由包括我们自己在内的几个小组完成，但关于TLR 7/8/9如何与核酸和其他配体相互作用并受核酸和其他配体调节以响应微生物病原体的主要未解决问题仍然存在。与TLR相比，NLR的结构研究非常有限。到目前为止，只有一个NLR LRR结构，即NLRX 1，已被解决，我们还表明，它直接结合RNA配体。凭借我们在表达，纯化，结晶和表征各种LRR蛋白方面的广泛专业知识，我们将研究TLR 7/8/9和NLRC 3/4/5中LRR结构域的结构，生物物理和功能特性，以及推进我们已经对TLR 5和NLRX 1的生产性研究。这些发现将解决TLR 7/8/9和NLRC 3/4/5与其同源配体的特异性相互作用所产生的结构和功能机制，并导致对先天免疫中受体激活和调节的理解。我们将利用我们以前对TLR 5和NLRX 1的研究来回答关于它们的信号传导机制以及它们如何被外部因子调节的关键问题。与Andrei Gudkov、Cynthia Leifer和Jenny Ting博士在这些受体的细胞方面的合作以及与Andrew Ward和大卫贝克博士在专门的生物物理方法上的合作将补充我们的生物物理和功能研究，并刺激激动剂和拮抗剂的开发，作为免疫受损或炎症性疾病的治疗剂。

DESCRIPTION (provided by applicant): Innate immunity provides a first line of defense against pathogen- or danger-associated molecular patterns. Among known innate receptors, Toll-like receptors (TLRs) and NOD-like receptors (NLRs) share a common structural motif that consists of multiple leucine-rich repeats (LRRs) with some variability in amino- acid residues and length of each repeat. Structural studies of LRRs of variable lymphocyte receptors (VLRs) in jawless fish have also shown that LRR domains are important in ligand recognition. Thus, the LRRs of TLRs and NLRs are essential for interaction with agonist ligands in order to initiate cellular signaling in innate immunity. Furthermore, when the LRR domain is disengaged from the signaling domains, it can negatively regulate innate immunity, by competitively binding to ligands. Thus, the ultimate goal of this study is to advance understanding of the structure and function of LRRs in TLRs and NLRs in ligand-induced activation and signaling. Structural and biophysical characterization of LRR domains in TLR1/2/3/4/5/6 have been accomplished by several groups, including our own, but major unresolved questions remain concerning how TLR7/8/9 interact with and are regulated by nucleic acid and other ligands in response to microbial pathogens. Compared to TLRs, structural investigation of NLRs has been extremely limited. To date, only one NLR LRR structure, that of NLRX1, has been solved and we have also shown that it directly binds RNA ligands. With our extensive expertise in expression, purification, crystallization and characterization of diverse LRR proteins, we will investigate structural, biophysical and functional properties of LRR domains in TLR7/8/9 and NLRC3/4/5, as well as advance our already productive studies of TLR5 and NLRX1. Such findings will address the structural and functional mechanisms that arise from the specific interactions of TLR7/8/9 and NLRC3/4/5 with their cognate ligands and lead to understanding of receptor activation and regulation in innate immunity. We will capitalize on our previous studies of TLR5 and NLRX1 to answer key questions about their signaling mechanisms and how they might be regulated by outside agents. Collaborations on cellular aspects on these receptors with Drs. Andrei Gudkov, Cynthia Leifer and Jenny Ting and on specialized biophysical approaches with Drs. Andrew Ward and David Baker will complement our biophysical and functional studies as well as stimulate development of agonists and antagonists as therapeutics in compromised immunity or in hyper- inflammatory diseases.