An AAGAB-to-CCDC32 handover mechanism controls the assembly of the AP2 adaptor complex

• 成果类型: Article
• 署名作者: Wan, Chun; Puscher, Harrison; Ouyang, Yan; Wu, Jingyi; Tian, Yuan; Li, Suzhao; Yin, Qian; Shen, Jingshi
• 署名单位: University of Colorado System; University of Colorado Boulder; State University System of Florida; Florida State University; State University System of Florida; Florida State University; University of Colorado System; University of Colorado Anschutz Medical Campus
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-12325
• DOI: 10.1073/pnas.2409341121
• 发表日期: 2024-08-20
• 关键词: molecular-mechanism; ap1s3 mutations; clathrin; RECRUITMENT; activation; DYNAMICS; ap-2

摘要

Vesicular transport relies on multimeric trafficking complexes to capture cargo and drive vesicle budding and fusion. Faithful assembly of the trafficking complexes is essential to their functions but remains largely unexplored. Assembly of AP2 adaptor, a heterotetrameric protein complex regulating clathrin- mediated endocytosis, is assisted by the chaperone AAGAB. Here, we found that AAGAB initiates AP2 assembly by stabilizing its alpha and sigma 2 subunits, but the AAGAB:alpha:sigma 2 complex cannot recruit additional AP2 subunits. We identified CCDC32 as another chaperone regulating AP2 assembly. CCDC32 recognizes the AAGAB:alpha:sigma 2 complex, and its binding leads to the formation of an alpha : sigma 2:CCDC32 ternary complex. The alpha : sigma 2:CCDC32 complex serves as a template that sequentially recruits the mu 2 and beta 2 subunits of AP2 to complete AP2 assembly, accompanied by CCDC32 release. The AP2- regulating function of CCDC32 is disrupted by a disease- causing mutation. These findings demonstrate that AP2 is assembled by a handover mechanism switching from AAGAB-based initiation complexes to CCDC32-based template complexes. A similar mechanism may govern the assembly of other trafficking complexes exhibiting the same configuration as AP2.