Tanabe Tsuyoshi, Chamaillard Mathias, Ogura Yasunori, Zhu Li, Qiu Su, Masumoto Junya, Ghosh Partho, Moran Anthony, Predergast Martina M, Tromp Gerard, Williams Charlene J, Inohara Naohiro, Núñez Gabriel
Department of Pathology and Comprehensive Cancer Center, University of Michigan Medical School, Ann Arbor, MI, USA.
EMBO J. 2004 Apr 7;23(7):1587-97. doi: 10.1038/sj.emboj.7600175. Epub 2004 Mar 25.
Multiple genetic variants of CARD15/NOD2 have been associated with susceptibility to Crohn's disease and Blau syndrome. NOD2 recognizes muramyl dipeptide (MDP) derived from bacterial peptidoglycan (PGN), but the molecular basis of recognition remains elusive. We performed systematic mutational analysis to gain insights into the function of NOD2 and molecular mechanisms of disease susceptibility. Using an archive of 519 mutations covering approximately 50% of the amino-acid residues of NOD2, the essential regulatory domains and specific residues of NOD2 involved in recognition of MDP were identified. The analysis revealed distinct roles for N-terminal and C-terminal leucine-rich repeats (LRRs) in the modulation of NOD2 activation and bacterial recognition. Within the C-terminal LRRs, variable residues predicted to form the beta-strand/betaturn structure were found to be essential for the response to MDP. In addition, we analyzed NOD1, a NOD2-related protein, revealing conserved and nonconserved amino-acid residues involved in PGN recognition. These results provide new insights into the molecular function and regulation of NOD2 and related NOD family proteins.
CARD15/NOD2的多种基因变异与克罗恩病和布劳综合征的易感性相关。NOD2可识别源自细菌肽聚糖（PGN）的胞壁酰二肽（MDP），但其识别的分子基础仍不清楚。我们进行了系统的突变分析，以深入了解NOD2的功能和疾病易感性的分子机制。利用一个包含519个突变的文库，覆盖了NOD2约50%的氨基酸残基，确定了NOD2中参与MDP识别的关键调节结构域和特定残基。分析揭示了N端和C端富含亮氨酸重复序列（LRR）在调节NOD2激活和细菌识别中的不同作用。在C端LRR中，预测形成β-链/β-转角结构的可变残基被发现对MDP反应至关重要。此外，我们分析了NOD1，一种与NOD2相关的蛋白，揭示了参与PGN识别的保守和非保守氨基酸残基。这些结果为NOD2及相关NOD家族蛋白的分子功能和调节提供了新的见解。
