Storici Francesca, Henneke Ghislaine, Ferrari Elena, Gordenin Dmitry A, Hübscher Ulrich, Resnick Michael A
Laboratory of Molecular Genetics, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA.
EMBO J. 2002 Nov 1;21(21):5930-42. doi: 10.1093/emboj/cdf587.
The conserved, structure-specific flap endonuclease FEN1 cleaves 5' DNA flaps that arise during replication or repair. To address in vivo mechanisms of flap cleavage, we developed a screen for human FEN1 mutants that are toxic when expressed in yeast. Two targets were revealed: the flexible loop domain and the catalytic site. Toxic mutants caused G(2) arrest and cell death and were unable to repair methyl methanesulfonate lesions. All the mutant proteins retained flap binding. Unlike the catalytic site mutants, which lacked cleavage of any 5' flaps, the loop mutants exhibited partial ability to cut 5' flaps when an adjacent single nucleotide 3' flap was present. We suggest that the flexible loop is important for efficient cleavage through positioning the 5' flap and the catalytic site.
保守的、结构特异性的瓣状核酸内切酶FEN1可切割复制或修复过程中产生的5' DNA瓣。为了研究瓣切割的体内机制，我们开发了一种筛选方法，用于筛选在酵母中表达时具有毒性的人类FEN1突变体。发现了两个靶点：柔性环结构域和催化位点。有毒突变体导致G2期阻滞和细胞死亡，并且无法修复甲磺酸甲酯损伤。所有突变蛋白都保留了对瓣的结合能力。与缺乏切割任何5' 瓣能力的催化位点突变体不同，当存在相邻的单核苷酸3' 瓣时，环突变体表现出部分切割5' 瓣的能力。我们认为，柔性环对于通过定位5' 瓣和催化位点进行高效切割很重要。
