PMID: 23999858

Authors:

Wang Y, Han X, Wu F, Leung JW, Lowery MG, Do H, Chen J, Shi C, Tian C, Li L, Gong W

Title:

Structure analysis of FAAP24 reveals single-stranded DNA-binding activity and domain functions in DNA damage response.

Journal:

Cell Res. 2013 Sep 3. doi: 10.1038/cr.2013.124.

Abstract:

The FANCM/FAAP24 heterodimer has distinct functions in protecting cells from complex DNA lesions such as interstrand crosslinks. These functions rely on the biochemical activity of FANCM/FAAP24 to recognize and bind to damaged DNA or stalled replication forks. However, the DNA-binding activity of this complex was not clearly defined. We investigated how FAAP24 contributes to the DNA-interacting functions of the FANCM/FAAP24 complex by acquiring the N-terminal and C-terminal solution structures of human FAAP24. Modeling of the FAAP24 structure indicates that FAAP24 may possess a high affinity toward single-stranded DNA (ssDNA). Testing of various FAAP24 mutations in vitro and in vivo validated this prediction derived from structural analyses. We found that the DNA-binding and FANCM-interacting functions of FAAP24, although both require the C-terminal (HhH)2 domain, can be distinguished by segregation-of-function mutations. These results demonstrate dual roles of FAAP24 in DNA damage response against crosslinking lesions, one through the formation of FANCM/FAAP24 heterodimer and the other via its ssDNA-binding activity required in optimized checkpoint activation.Cell Research advance online publication 3 September 2013; doi:10.1038/cr.2013.124.