Download MendeleyThe human ATAD5 has evolved unique structural elements to function exclusively as a PCNA unloader.
Wang, F., He, Q., Yao, N.Y., O'Donnell, M.E., Li, H.(2024) Nat Struct Mol Biol 31: 1680-1691
- PubMed: 38871854
- DOI: https://doi.org/10.1038/s41594-024-01332-4
- Primary Citation of Related Structures:
8UI7, 8UI8, 8UI9, 8UII - PubMed Abstract:
Humans have three different proliferating cell nuclear antigen (PCNA) clamp-loading complexes: RFC and CTF18-RFC load PCNA onto DNA, but ATAD5-RFC can only unload PCNA from DNA. The underlying structural basis of ATAD5-RFC unloading is unknown. We show here that ATAD5 has two unique locking loops that appear to tie the complex into a rigid structure, and together with a domain that plugs the DNA-binding chamber, prevent conformation changes required for DNA binding, likely explaining why ATAD5-RFC is exclusively a PCNA unloader. These features are conserved in the yeast PCNA unloader Elg1-RFC. We observe intermediates in which PCNA bound to ATAD5-RFC exists as a closed planar ring, a cracked spiral or a gapped spiral. Surprisingly, ATAD5-RFC can open a PCNA gap between PCNA protomers 2 and 3, different from the PCNA protomers 1 and 3 gap observed in all previously characterized clamp loaders.
Organizational Affiliation:
Department of Structural Biology, Van Andel Institute, Grand Rapids, MI, USA.
