Department of Medicine, University of California, San Diego, La Jolla, CA 92093, USA.
J Cell Biol. 2012 Oct 1;199(1):39-48. doi: 10.1083/jcb.201205109. Epub 2012 Sep 24.
The products of genes that cause cerebral cavernous malformations (CCM1/KRIT1, CCM2, and CCM3) physically interact. CCM1/KRIT1 links this complex to endothelial cell (EC) junctions and maintains junctional integrity in part by inhibiting RhoA. Heart of glass (HEG1), a transmembrane protein, associates with KRIT1. In this paper, we show that the KRIT1 band 4.1, ezrin, radixin, and moesin (FERM) domain bound the HEG1 C terminus (K(d) = 1.2 µM) and solved the structure of this assembly. The KRIT1 F1 and F3 subdomain interface formed a hydrophobic groove that binds HEG1(Tyr(1,380)-Phe(1,381)), thus defining a new mode of FERM domain-membrane protein interaction. This structure enabled design of KRIT1(L717,721A), which exhibited a >100-fold reduction in HEG1 affinity. Although well folded and expressed, KRIT1(L717,721A) failed to target to EC junctions or complement the effects of KRIT1 depletion on zebrafish cardiovascular development or Rho kinase activation in EC. These data establish that this novel FERM-membrane protein interaction anchors CCM1/KRIT1 at EC junctions to support cardiovascular development.
导致脑海绵状血管畸形的基因产物（CCM1/KRIT1、CCM2 和 CCM3）相互作用。CCM1/KRIT1 将这个复合物与内皮细胞（EC）连接，并通过抑制 RhoA 部分维持连接的完整性。跨膜蛋白 Heart of glass（HEG1）与 KRIT1 相关。在本文中，我们表明 KRIT1 带 4.1、埃兹蛋白、radixin 和膜突蛋白（FERM）结构域结合了 HEG1 的 C 末端（K(d)=1.2 µM）并解析了这个组装体的结构。KRIT1 F1 和 F3 亚结构域界面形成了一个疏水槽，结合了 HEG1（Tyr(1,380)-Phe(1,381)），从而定义了 FERM 结构域与膜蛋白相互作用的新模式。该结构使 KRIT1(L717,721A)的设计成为可能，其对 HEG1 的亲和力降低了>100 倍。尽管 KRIT1(L717,721A)折叠良好且表达正常，但它未能靶向 EC 连接或补充 KRIT1 耗竭对斑马鱼心血管发育或 EC 中 Rho 激酶激活的影响。这些数据表明，这种新型 FERM-膜蛋白相互作用将 CCM1/KRIT1 锚定在 EC 连接上，以支持心血管发育。
