Xu Dong
Zhou Gong
Ling-Yun Qin
Shuai Yang
Yue-Ling Zhu
Xiang Wang
Delin Zhang
Tingting Zou
Ping Yin
Chun Tang
1 National Key Laboratory of Crop Genetic Improvement and National Center of Plant Gene Research, Huazhong Agricultural University, Wuhan 430070, China;
2 CAS Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic Molecular Physics, and National Center for Magnetic Resonance at Wuhan, Wuhan Institute of Physics and Mathematics of the Chinese Academy of Sciences, Wuhan 430071, China
Funds: The work was supported by National Key R&D Program of China (2016YFA0501200 to C. Tang), the Chinese Ministry of Science and Technology (2015CB910900 to P. Yin), the National Natural Science Foundation of China (91753132 and 31770799 to C. Tang, 31722017 to P. Yin, 31400735 to Z. Gong, 31400644 to X. Dong), the Fok Ying-Tong Education Foundation (151021 to P. Yin), and the Fundamental Research Funds for the Central Universities (2017PY031 to P. Yin).
Received Date: 2018-01-14
Abstract
Abstract
N6-methyladenosine (m6A), a ubiquitous RNA modification, is installed by METTL3-METTL14 complex. The structure of the heterodimeric complex between the methyltransferase domains (MTDs) of METTL3 and METTL14 has been previously determined. However, the MTDs alone possess no enzymatic activity. Here we present the solution structure for the zinc finger domain (ZFD) of METTL3, the inclusion of which fulfills the methyltransferase activity of METTL3-METTL14. We show that the ZFD specifically binds to an RNA containing 5'-GGACU-3' consensus sequence, but does not to one without. The ZFD thus serves as the target recognition domain, a structural feature previously shown for DNA methyltransferases, and cooperates with the MTDs of METTL3-METTL14 for catalysis. However, the interaction between the ZFD and the specific RNA is extremely weak, with the binding affinity at several hundred micromolar under physiological conditions. The ZFD contains two CCCH-type zinc fingers connected by an anti-parallel β-sheet. Mutational analysis and NMR titrations have mapped the functional interface to a contiguous surface. As a division of labor, the RNAbinding interface comprises basic residues from zinc finger 1 and hydrophobic residues from β-sheet and zinc finger 2. Further we show that the linker between the ZFD and MTD of METTL3 is flexible but partially folded, which may permit the cooperation between the two domains during catalysis. Together, the structural characterization of METTL3 ZFD paves the way to elucidate the atomic details of the entire process of RNA m6A modification.Keywords: RNA modification,
N6-methyladenosine,
METTL3,
target recognition domain,
zinc finger,
paramagnetic relaxation enhancement
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