Luo Meng, Jia Xudong, Wang Zi-Wen, Yang Jin-Yu, Wang Wen, Chen Jiazhen, Ou Jun-Ying, Feng Jian-Xiong, Yu Bing, Wang Sheng, Huang Lin, Morgan Neil V, Deng Kai, Chen Tongsheng, Zhang Qinfen, Gao Song
State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou 510060, China.
State Key Lab for Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China.
Nucleic Acids Res. 2025 May 22;53(10). doi: 10.1093/nar/gkaf484.
The Schlafen (SLFN) family of proteins are a group of DNA/RNA processing enzymes with emerging importance in human health and disease, where their functions are implicated in a variety of immunological and anti-tumor processes. Here, we present the cryo-electron microscopy structure of full-length human SLFN14, a member with antiviral activity and linked to an inherited bleeding disorder. SLFN14 is composed of an RNase domain, a SWADL domain, and a two-lobe helicase domain. SLFN14 exhibited strong RNase activity over different substrates, and the positively charged patches at the valley of the RNase domain, which contains the thrombocytopenia-related missense mutation sites, are crucial for binding oligonucleotides. SLFN14 lacks helicase activity, which can be attributed to the inability to bind ATP and the absence of positive charges at the canonical DNA-binding site of its RecA-like folds. SLFN14 is structurally similar to SLFN11, but differs from SLFN5 in the orientation of the helicase domain. Live-cell fluorescence resonance energy transfer (FRET) assays and AlphaFold2 analysis hinted that SLFN14 may adopt multiple conformations in cells. These results provide detailed structural and biochemical features of SLFN14, and greatly expand our knowledge of the functional diversity of the SLFN family.
施拉芬（SLFN）蛋白家族是一类DNA/RNA加工酶，在人类健康和疾病中日益重要，其功能涉及多种免疫和抗肿瘤过程。在此，我们展示了全长人类SLFN14的冷冻电子显微镜结构，它是一种具有抗病毒活性且与一种遗传性出血性疾病相关的成员。SLFN14由一个核糖核酸酶结构域、一个SWADL结构域和一个双叶解旋酶结构域组成。SLFN14对不同底物表现出强大的核糖核酸酶活性，核糖核酸酶结构域谷底带正电荷的区域（包含与血小板减少相关的错义突变位点）对于结合寡核苷酸至关重要。SLFN14缺乏解旋酶活性，这可归因于其无法结合ATP以及在其类RecA折叠的典型DNA结合位点缺乏正电荷。SLFN14在结构上与SLFN11相似，但在解旋酶结构域的方向上与SLFN5不同。活细胞荧光共振能量转移（FRET）分析和AlphaFold2分析表明，SLFN14在细胞中可能采取多种构象。这些结果提供了SLFN14详细的结构和生化特征，并极大地扩展了我们对SLFN家族功能多样性的认识。
