Zipper head mechanism of telomere synthesis by human telomerase  

作　　者：Futang Wan Yongbo Ding Yuebin Zhang Zhenfang Wu Shaobai Li Lin Yang Xiangyu Yan Pengfei Lan Guohui Li Jian Wu Ming Lei 

机构地区：[1]Ninth People’s Hospital,Shanghai Jiao Tong University School of Medicine,Shanghai,China [2]Shanghai Institute of Precision Medicine,Shanghai,China [3]CAS Center for Excellence in Molecular Cell Science,Shanghai Institute of Biochemistry and Cell Biology,Chinese Academy of Sciences,Shanghai,China [4]University of Chinese Academy of Sciences,Beijing,China [5]Laboratory of Molecular Modeling and Design,State Key Laboratory of Molecular Reaction Dynamics,Dalian Institute of Chemical Physics,Chinese Academy of Sciences,Dalian,Liaoning,China [6]Renji Hospital,Shanghai Jiao Tong University School of Medicine,Shanghai,China [7]State Key Laboratory of Oncogenes and Related Genes,Shanghai Jiao Tong University School of Medicine,Shanghai,China

出　　处：《Cell Research》2021年第12期1275-1290,共16页细胞研究（英文版）

基　　金：This work was supported by the National Key R&D Program of China(2018YFA0107004 and 2018YFC2000100 to M.L.,and 2019YFA0709400 to G.L.);the National Natural Science Foundation of China(31930063 to M.L.,21625302 and 21933010 to G.L.,and 32000843 to F.W.);the Shanghai Municipal Health Commission and Collaborative Innovation Cluster Project(2019CXJQ01 to M.L.);the Shanghai Municipal Education Commission—Gaofeng Clinical Medicine Grant Support(20181711 to J.W.).

摘　　要：Telomerase,a multi-subunit ribonucleoprotein complex,is a unique reverse transcriptase that catalyzes the processive addition of a repeat sequence to extend the telomere end using a short fragment of its own RNA component as the template.Despite recent structural characterizations of human and Tetrahymena telomerase,it is still a mystery how telomerase repeatedly uses its RNA template to synthesize telomeric DNA.Here,we report the cryo-EM structure of human telomerase holoenzyme bound with telomeric DNA at resolutions of 3.5 Åand 3.9 Åfor the catalytic core and biogenesis module,respectively.The structure reveals that a leucine residue Leu980 in telomerase reverse transcriptase(TERT)catalytic subunit functions as a zipper head to limit the length of the short primer–template duplex in the active center.Moreover,our structural and computational analyses suggest that TERT and telomerase RNA(hTR)are organized to harbor a preformed active site that can accommodate short primer–template duplex substrates for catalysis.Furthermore,our findings unveil a double-fingers architecture in TERT that ensures nucleotide addition processivity of human telomerase.We propose that the zipper head Leu980 is a structural determinant for the sequence-based pausing signal of DNA synthesis that coincides with the RNA element-based physical template boundary.Functional analyses unveil that the non-glycine zipper head plays an essential role in both telomerase repeat addition processivity and telomere length homeostasis.In addition,we also demonstrate that this zipper head mechanism is conserved in all eukaryotic telomerases.Together,our study provides an integrated model for telomerase-mediated telomere synthesis.

关 键 词：TEMPLATE SYNTHESIS MECHANISM 

分 类 号：Q55[生物学—生物化学]