Identification of an expanded binding surface on the FADD death domain responsible for interaction with CD95/Fas.
The initiation of programmed cell death at CD95 (Fas, Apo-1) is achieved by forming a death-inducing signaling complex (DISC) at the cytoplasmic membrane surface. Assembly of the DISC has been proposed to occur via homotypic interactions between the death domain (DD) of FADD and the cytoplasmic domain of CD95. Previous analysis of the FADD/CD95 interaction led to the identification of a putative CD95 binding surface within FADD DD formed by alpha helices 2 and 3. More detailed analysis of the CD95/FADD DD interaction now demonstrates that a bimodal surface exists in the FADD DD for interaction with CD95. An expansive surface on one side of the domain is composed of elements in alpha helices 1, 2, 3, 5, and 6. This major surface is common to many proteins harboring this motif, whether or not they are associated with programmed cell death. A secondary surface resides on the opposite face of the domain and involves residues in helices 3 and 4. The major surface is topologically similar to the protein interaction surface identified in Drosophila Tube DD and the death effector domain of hamster PEA-15, two physiologically unrelated proteins which interact with structurally unrelated binding partners. These results demonstrate the presence of a structurally conserved surface within the DD which can mediate protein recognition with homo- and heterotypic binding partners, whereas a second surface may be responsible for stabilizing the higher order complex in the DISC.
Laboratory of Molecular Biophysics, The Rockefeller University, New York, New York 10021, USA.
Justine M
JM
Hill
Gaku
G
Morisawa
Tad
T
Kim
Ted
T
Huang
Yu
Y
Wei
Yufeng
Y
Wei
Milton H
MH
Werner
D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D000818:Animals; D002352:Carrier Proteins / Q000737:chemistry* / Q000378:metabolism; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism; D002470:Cell Survival; D003593:Cytoplasm / Q000378:metabolism; D018076:DNA, Complementary / Q000378:metabolism; D004330:Drosophila / Q000378:metabolism; D053200:Fas-Associated Death Domain Protein; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D011233:Precipitin Tests; D011485:Protein Binding; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D013997:Time Factors; D019014:fas Receptor / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*
D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D018076:DNA, Complementary; C505533:FADD protein, human; D053200:Fas-Associated Death Domain Protein; D019014:fas Receptor