title: A gating mechanism for Pi release governs the mRNA unwinding by eIF4AI during translation initiation.
abstract: Eukaryotic translation initiation factor eIF4AI, the founding member of DEAD-box helicases, undergoes ATP hydrolysis-coupled conformational changes to unwind mRNA secondary structures during translation initiation. However, the mechanism of its coupled enzymatic activities remains unclear. Here we report that a gating mechanism for Pi release controlled by the inter-domain linker of eIF4AI regulates the coupling between ATP hydrolysis and RNA unwinding. Molecular dynamic simulations and experimental results revealed that, through forming a hydrophobic core with the conserved SAT motif of the N-terminal domain and I357 from the C-terminal domain, the linker gated the release of Pi from the hydrolysis site, which avoided futile hydrolysis cycles of eIF4AI. Further mutagenesis studies suggested this linker also plays an auto-inhibitory role in the enzymatic activity of eIF4AI, which may be essential for its function during translation initiation. Overall, our results reveal a novel regulatory mechanism that controls eIF4AI-mediated mRNA unwinding and can guide further mechanistic studies on other DEAD-box helicases.
authors.affiliation: Key Laboratory of Metabolism and Molecular Medicine, the Ministry of Education, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Fudan University, Shanghai 200032, China Drug Discovery and Design Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China.
authors.forename: Junyan
authors.initials: J
authors.lastname: Lu
authors.affiliation: Key Laboratory of Metabolism and Molecular Medicine, the Ministry of Education, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Fudan University, Shanghai 200032, China.
authors.forename: Chenxiao
authors.initials: C
authors.lastname: Jiang
authors.affiliation: Key Laboratory of Metabolism and Molecular Medicine, the Ministry of Education, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Fudan University, Shanghai 200032, China.
authors.forename: Xiaojing
authors.initials: X
authors.lastname: Li
authors.affiliation: Key Laboratory of Metabolism and Molecular Medicine, the Ministry of Education, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Fudan University, Shanghai 200032, China.
authors.forename: Lizhi
authors.initials: L
authors.lastname: Jiang
authors.affiliation: Key Laboratory of Metabolism and Molecular Medicine, the Ministry of Education, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Fudan University, Shanghai 200032, China.
authors.forename: Zengxia
authors.initials: Z
authors.lastname: Li
authors.affiliation: Chemical Genetics Laboratory, RIKEN, Wako, Saitama, 351-0198, Japan.
authors.forename: Tilman
authors.initials: T
authors.lastname: Schneider-Poetsch
authors.affiliation: Department of Chemistry, Shanghai Key Lab of Chemical Biology for Protein Research & Institutes of Biomedical Sciences, Fudan University, Shanghai 200433, China.
authors.forename: Jianwei
authors.initials: J
authors.lastname: Liu
authors.affiliation: Drug Discovery and Design Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China.
authors.forename: Kunqian
authors.initials: K
authors.lastname: Yu
authors.affiliation: Department of Pharmacology & Molecular Sciences and Department of Oncology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
authors.forename: Jun O
authors.initials: JO
authors.lastname: Liu
authors.affiliation: Drug Discovery and Design Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China.
authors.forename: Hualiang
authors.initials: H
authors.lastname: Jiang
authors.affiliation: Drug Discovery and Design Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China cluo@simm.ac.cn.
authors.forename: Cheng
authors.initials: C
authors.lastname: Luo
authors.affiliation: Key Laboratory of Metabolism and Molecular Medicine, the Ministry of Education, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Fudan University, Shanghai 200032, China yongjundang@fudan.edu.cn.
authors.forename: Yongjun
authors.initials: Y
authors.lastname: Dang
mesh_terms: D000244:Adenosine Diphosphate / Q000737:chemistry / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000737:chemistry / Q000378:metabolism; D020816:Amino Acid Motifs; D039601:Eukaryotic Initiation Factor-4A / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D056004:Molecular Dynamics Simulation; D009154:Mutation; D010442:Peptide Chain Initiation, Translational; D010710:Phosphates / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D012333:RNA, Messenger / Q000737:chemistry* / Q000378:metabolism
chemical_list: D010710:Phosphates; D012333:RNA, Messenger; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D039601:Eukaryotic Initiation Factor-4A