Structures of human insulin-degrading enzyme reveal a new substrate recognition mechanism

Article

关键词: AMYLOID BETA-PROTEIN;    MITOCHONDRIAL PROCESSING PEPTIDASE;    BUD-SITE SELECTION;    ALZHEIMERS-DISEASE;    IN-VIVO;    DEGRADATION;    DOMAIN;    INSULYSIN;    GLUCAGON;    AMYLIN;   

DOI  :  10.1038/nature05143

来源: SCIE

【 摘 要 】

Insulin-degrading enzyme (IDE), a Zn2+-metalloprotease, is involved in the clearance of insulin and amyloid-beta (refs 1 - 3). Loss-of-function mutations of IDE in rodents cause glucose intolerance and cerebral accumulation of amyloid-beta, whereas enhanced IDE activity effectively reduces brain amyloid-beta ( refs 4 - 7). Here we report structures of human IDE in complex with four substrates ( insulin B chain, amyloid-beta peptide ( 1 - 40), amylin and glucagon). The amino- and carboxy-terminal domains of IDE (IDE-N and IDE-C, respectively) form an enclosed cage just large enough to encapsulate insulin. Extensive contacts between IDE-N and IDE-C keep the degradation chamber of IDE inaccessible to substrates. Repositioning of the IDE domains enables substrate access to the catalytic cavity. IDE uses size and charge distribution of the substrate-binding cavity selectively to entrap structurally diverse polypeptides. The enclosed substrate undergoes conformational changes to form beta-sheets with two discrete regions of IDE for its degradation. Consistent with this model, mutations disrupting the contacts between IDE-N and IDE-C increase IDE catalytic activity 40-fold. The molecular basis for substrate recognition and allosteric regulation of IDE could aid in designing IDE-based therapies to control cerebral amyloid-beta and blood sugar concentrations(1,8,9).

【 授权许可】

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