Download MendeleyOligomer-to-monomer transition underlies the chaperone function of AAGAB in AP1/AP2 assembly.
Tian, Y., Datta, I., Yang, R., Wan, C., Wang, B., Crisman, L., He, H., Brautigam, C.A., Li, S., Shen, J., Yin, Q.(2023) Proc Natl Acad Sci U S A 120: e2205199120-e2205199120
- PubMed: 36598941
- DOI: https://doi.org/10.1073/pnas.2205199120
- Primary Citation of Related Structures:
7TWD - PubMed Abstract:
Assembly of protein complexes is facilitated by assembly chaperones. Alpha and gamma adaptin-binding protein (AAGAB) is a chaperone governing the assembly of the heterotetrameric adaptor complexes 1 and 2 (AP1 and AP2) involved in clathrin-mediated membrane trafficking. Here, we found that before AP1/2 binding, AAGAB exists as a homodimer. AAGAB dimerization is mediated by its C-terminal domain (CTD), which is critical for AAGAB stability and is missing in mutant proteins found in patients with the skin disease punctate palmoplantar keratoderma type 1 (PPKP1). We solved the crystal structure of the dimerization-mediating CTD, revealing an antiparallel dimer of bent helices. Interestingly, AAGAB uses the same CTD to recognize and stabilize the γ subunit in the AP1 complex and the α subunit in the AP2 complex, forming binary complexes containing only one copy of AAGAB. These findings demonstrate a dual role of CTD in stabilizing resting AAGAB and binding to substrates, providing a molecular explanation for disease-causing AAGAB mutations. The oligomerization state transition mechanism may also underlie the functions of other assembly chaperones.
Organizational Affiliation:
Department of Biological Science and Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306.
