Laboratory of Structural Immunology, CAS Key Laboratory of Innate Immunity and Chronic Disease, School of Life Sciences and Medical Center, University of Science and Technology of China, Hefei, China.
Laboratory of Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA.
FEBS J. 2018 Jul;285(14):2691-2707. doi: 10.1111/febs.14514. Epub 2018 Jun 14.
The zebrafish genome encodes homologs for most of the proteins involved in inflammatory pathways; however, the molecular components and activation mechanisms of fish inflammasomes are largely unknown. ASC [apoptosis-associated speck-like protein containing a caspase-recruitment domain (CARD)] is the only adaptor involved in the formation of multiple types of inflammasomes. Here, we demonstrate that zASC is also involved in inflammasome activation in zebrafish. When overexpressed in vitro and in vivo in zebrafish, both the zASC and zASC pyrin domain (PYD) proteins form speck and filament structures. Importantly, the crystal structures of the N-terminal PYD and C-terminal CARD of zebrafish ASC were determined independently as two separate entities fused to maltose-binding protein. Structure-guided mutagenesis revealed the functional relevance of the PYD hydrophilic surface found in the crystal lattice. Finally, the fish caspase-1 homolog Caspy, but not the caspase-4/11 homolog Caspy2, interacts with zASC through homotypic PYD-PYD interactions, which differ from those in mammals. These observations establish the conserved and unique structural/functional features of the zASC-dependent inflammasome pathway.
Structural data are available in the PDB under accession numbers 5GPP and 5GPQ.
斑马鱼基因组编码了大多数参与炎症途径的蛋白质的同源物;然而，鱼类炎症小体的分子成分和激活机制在很大程度上是未知的。 ASC [凋亡相关斑点样蛋白包含半胱氨酸蛋白酶募集域（CARD）]是参与多种炎症小体形成的唯一衔接蛋白。在这里，我们证明 zASC 也参与斑马鱼炎症小体的激活。当在体外和体内过表达时，zASC 和 zASC 吡咯烷二酮（PYD）蛋白在斑马鱼中均形成斑点和纤维结构。重要的是，斑马鱼 ASC 的 N 端 PYD 和 C 端 CARD 的晶体结构分别作为两个独立的实体融合到麦芽糖结合蛋白中确定。基于结构的诱变揭示了在晶格中发现的 PYD 亲水表面的功能相关性。最后，鱼 Caspase-1 同源物 Caspy 而不是 Caspase-4/11 同源物 Caspy2 通过同种型 PYD-PYD 相互作用与 zASC 相互作用，这与哺乳动物中的不同。这些观察结果确立了 zASC 依赖性炎症小体途径的保守和独特的结构/功能特征。
结构数据可在 PDB 中以访问号 5GPP 和 5GPQ 的形式获得。
