Solution Structure of the RAIDD CARD and Model for CARD/CARD Interaction in Caspase-2 and Caspase-9 Recruitment

Abstract

Apoptosis requires recruitment of caspases by receptor-associated adaptors through homophilic interactions between the CARDs (caspase recruitment domains) of adaptor proteins and prodomains of caspases. We have solved the CARD structure of the RAIDD adaptor protein that recruits ICH-1/caspase-2. It consists of six tightly packed helices arranged in a topology homologous to the Fas death domain. The surface contains a basic and an acidic patch on opposite sides. This polarity is conserved in the ICH-1 CARD as indicated by homology modeling. Mutagenesis data suggest that these patches mediate CARD/CARD interaction between RAIDD and ICH-1. Subsequent modeling of the CARDs of Apaf-1 and caspase-9, as well as Ced-4 and Ced-3, showed that the basic/acidic surface polarity is highly conserved, suggesting a general mode for CARD/CARD interaction.

Requirement of cooperative functions of two repeated death effector domains in caspase‐8 and in MC159 for induction and inhibition of apoptosis, respectively

“…To clarify the molecular mechanism of induction and inhibition of apoptosis by Casp8NC-DED and MC159, respectively, it is necessary to determine whether MC159 inhibits the binding of caspase-8 to FLASH and/or FADD in mammalian cells. DED and CARD were reported to possess similar structures with ␣-helixes based on NMR analyses (Eberstadt et al 1997;Chou et al 1998). Their functions may also be similar, because they exist in the prodomains of caspase or the N-terminal region of an effector molecule for apoptosis, such as FADD and Apaf-1.…”

RAIDD aggregation facilitates apoptotic death of PC12 cells and sympathetic neurons

“…Homology with human RAIDD is shown in Figure 1a. Particularly striking is the degree of conservation within the shaded N-terminal CARD region (as defined by nuclear magnetic resonance (NMR), Chou et al 23 ). Within this region, there is a high degree of homology with the N-terminal CARD of rat caspase 2.…”

“…Within this region, there is a high degree of homology with the N-terminal CARD of rat caspase 2. 20 For the sequence spanning residues 4-93 of rat RAIDD, which defines the six helices of the RAIDD CARD, 23 there is 54.4% similarity and 28.9% identity with rat caspase 2 ( Figure 1b).…”

“…The constructs utilized are depicted in Figure 2. These include: RAIDDM, identical to wild-type (WT) RAIDD, except for mutation L27F, which has previously been shown to prevent the interaction between human RAIDD and caspase 2 CARDs; 8 RAIDD(1-83), encoding residues 1-83 of WT RAIDD, thus encompassing the initially identified area of homology with caspase 2 CARD; 8 RAIDD(1-117), encoding residues 1-117 of WT RAIDD, thus encompassing the full sixhelical loop of the CARD, as defined by NMR; 23 Figure 1 Diagram of homology between rat and human RAIDD. The sequence of rat RAIDD is compared to the reported sequence of human RAIDD/CRADD.…”

“…Diagram of homology between the CARDs of rat caspase 2 and rat RAIDD. The CARD, as defined by Chou et al 23 of rat RAIDD is compared to the CARD of rat caspase 2. 20 The middle row indicates common AAs or conservative substitutions.…”