An engineered construct of cFLIP provides insight into DED1 structure and interactions

Alexandra E Panaitiu, Tamar Basiashvili, Dale F Mierke, Maria Pellegrini

Structure. 2021 Nov 13;S0969-2126(21)00379-8. doi: 10.1016/j.str.2021.10.011. Online ahead of print.

https://www.sciencedirect.com/science/article/pii/S0969212621003798

https://authors.elsevier.com/a/1e6LY3SNvb-9mM

A look at our structure of cFLIP DED1: the buried DED1/DED2 interface (shown left in a tandem DED) was substituted with the soluble FADD sequence (middle in yellow) to generate a soluble cFLIP DED1 chimera (right)

Cellular FLICE-like inhibitory protein (cFLIP) is a member of the Death Domain superfamily with pivotal roles in many cellular processes and disease states, including cancer and autoimmune disorders. In the context of the death-inducing signaling complex (DISC), cFLIP isoforms regulate extrinsic apoptosis by controlling procaspase-8 activation. The function of cFLIP is mediated through a series of protein-protein interactions, engaging the two N-terminal death effector domains (DEDs). Here, we solve the structure of an engineered DED1 domain of cFLIP using solution nuclear magnetic resonance (NMR) and we define the interaction with FADD and calmodulin, protein-protein interactions that regulate the function of cFLIP in the DISC. cFLIP DED1 assumes a canonical DED fold characterized by six α helices and is able to bind calmodulin and FADD through two separate interfaces. Our results clearly demonstrate the role of DED1 in the cFLIP/FADD association and contribute to the understanding of the assembly of DISC filaments.