3siq
From Proteopedia
Crystal Structure of autoinhibited dIAP1-BIR1 domain
Structural highlights
FunctionDIAP1_DROME Anti-apoptotic protein which functions as a caspase regulator, using its E3 ubiquitin-protein ligase activity to smother caspase activity. Binds, ubiquitinates and inactivates initiator caspase Dronc, and effector caspases Drice and Dcp-1. Acts as a Nedd8-E3 ubiquitin-protein ligase for Drice. Suppresses apoptosis by targeting the apoptosome for ubiquitination and inactivation. Plays an important role in cell motility. Overexpression suppresses rpr and hid-dependent cell death in the eye. Interaction of Diap1 with Dronc is required to suppress Dronc-mediated cell death through Diap1-mediated ubiquitination of Dronc. Acts as a positive regulator of Wnt signaling.[1] [2] [3] [4] [5] [6] Publication Abstract from PubMedThe Drosophila inhibitor of apoptosis protein DIAP1 exists in an auto-inhibited conformation, unable to suppress the effector caspase drICE. Auto-inhibition is disabled by caspase-mediated cleavage of DIAP1 after Asp20. The cleaved DIAP1 binds to mature drICE, inhibits its protease activity, and, presumably, also targets drICE for ubiquitylation. DIAP1-mediated suppression of drICE is effectively antagonized by the pro-apoptotic proteins Reaper, Hid, and Grim (RHG). Despite rigorous effort, the molecular mechanisms behind these observations are enigmatic. Here we report a 2.4 A crystal structure of uncleaved DIAP1-BIR1, which reveals how the amino-terminal sequences recognize a conserved surface groove in BIR1 to achieve auto-inhibition, and a 3.5 A crystal structure of active drICE bound to cleaved DIAP1-BIR1, which provides a structural explanation to DIAP1-mediated inhibition of drICE. These structures and associated biochemical analyses, together with published reports, define the molecular determinants that govern the interplay among DIAP1, drICE and the RHG proteins. Structural mechanisms of DIAP1 auto-inhibition and DIAP1-mediated inhibition of drICE.,Li X, Wang J, Shi Y Nat Commun. 2011 Aug 2;2:408. doi: 10.1038/ncomms1418. PMID:21811237[7] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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