Internal motions prime cIAP1 for rapid activation.
Cellular inhibitor of apoptosis 1 (cIAP1) is a ubiquitin ligase with critical roles in the control of programmed cell death and NF-κB signaling. Under normal conditions, the protein exists as an autoinhibited monomer, but proapoptotic signals lead to its dimerization, activation and proteasomal degradation. This view of cIAP1 as a binary switch has been informed by static structural studies that cannot access the protein's dynamics. Here, we use NMR spectroscopy to study micro- and millisecond motions of specific domain interfaces in human cIAP1 and use time-resolved small-angle X-ray scattering to observe the global conformational changes necessary for activation. Although motions within each interface of the 'closed' monomer are insufficient to activate cIAP1, they enable associations with catalytic partners and activation factors. We propose that these internal motions facilitate rapid peptide-induced opening and dimerization of cIAP1, which undergoes a dramatic spring-loaded structural transition.
Department of Early Discovery Biochemistry, Genentech, South San Francisco, California, USA.
Aaron H
AH
Phillips
Department of Early Discovery Biochemistry, Genentech, South San Francisco, California, USA.
Allyn J
AJ
Schoeffler
Stanford Synchrotron Radiation Lightsource, Stanford Linear Accelerator Center National Laboratory, Menlo Park, California, USA.
Tsutomu
T
Matsui
Stanford Synchrotron Radiation Lightsource, Stanford Linear Accelerator Center National Laboratory, Menlo Park, California, USA.
Thomas M
TM
Weiss
Department of Early Discovery Biochemistry, Genentech, South San Francisco, California, USA.
John W
JW
Blankenship
Department of Early Discovery Biochemistry, Genentech, South San Francisco, California, USA.
Kerry
K
Zobel
Department of Biochemical and Cellular Pharmacology, Genentech, South San Francisco, California, USA.
Anthony M
AM
Giannetti
Department of Early Discovery Biochemistry, Genentech, South San Francisco, California, USA.
Erin C
EC
Dueber
Department of Early Discovery Biochemistry, Genentech, South San Francisco, California, USA.
Wayne J
WJ
Fairbrother
D006801:Humans; D051034:Inhibitor of Apoptosis Proteins / Q000737:chemistry* / Q000378:metabolism*; D007700:Kinetics; D008958:Models, Molecular; D019906:Nuclear Magnetic Resonance, Biomolecular; D011485:Protein Binding; D011487:Protein Conformation; D055503:Protein Multimerization; D017434:Protein Structure, Tertiary; D053838:Scattering, Small Angle; D025801:Ubiquitin / Q000378:metabolism; D044764:Ubiquitin-Activating Enzymes / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases; D014961:X-Ray Diffraction
D051034:Inhibitor of Apoptosis Proteins; D025801:Ubiquitin; C494833:BIRC2 protein, human; D044767:Ubiquitin-Protein Ligases; D044764:Ubiquitin-Activating Enzymes