Abstract 1286: FANCA binds to nucleic acids and stimulates endonuclease activity of FEN1.

Abstract

Abstract Fanconi anemia is a rare autosomal recessive or X-linked genetic disease characterized by progressive bone marrow failure, various developmental anomalies, and cancer predisposition. Fanconi anemia complementation group A (FANCA) gene is one of the 15 disease-causing genes and has been found to be mutated in ∼60% of Fanconi anemia patients. Except for its constituent role in the ubiquitin ligase of the Fanconi anemia core complex, no other biochemical activity has been identified thus far. Using purified protein, we observed that human FANCA has intrinsic affinity to nucleic acids. FANCA binds to both single-stranded and double-stranded DNA; however, its affinity to single-stranded DNA is dramatically higher. FANCA also binds to RNA with an intriguingly higher affinity than its DNA counterpart. A patient-derived FANCA truncation mutant, Q772X, has diminished affinity to both DNA and RNA. On the contrary, the complementing C-terminal fragment of Q772X, C772-1455, retains the differentiated nucleic acids binding activity (RNA>ssDNA>dsDNA), indicating that the nucleic acids binding domain of FANCA is primarily located at its C-terminus. Using DNA and RNA ladders, we determined that the minimum numbers of nucleotides required for FANCA recognition are ∼30 for both DNA and RNA. By testing the affinity between FANCA and a variety of DNA structures, we found that a 5’ flap or tail on DNA facilitates its interaction with FANCA. In addition, we observed that FANCA greatly stimulates the endonuclease activity of flap endonuclease 1 (FEN1), which processes 5’ flap structures. Our study reported that purified human FANCA binds to nucleic acids with strong preference for single-stranded forms. Our finding suggests that FANCA FANCA may participate in maintenance of replication forks by regulating removal of Okazaki fragment during maturation of lagging strand replication. Citation Format: Liangyue Qian, Fenghua Yuan, Paola Rodriguez-Tello, Xinliang Zhao, Limin Song, Gennaro D'Urso, Chaitanya Jain, Yanbin Zhang. FANCA binds to nucleic acids and stimulates endonuclease activity of FEN1. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1286. doi:10.1158/1538-7445.AM2013-1286