title: New insights into the enzymatic role of EF-G in ribosome recycling.
abstract: During translation, elongation factor G (EF-G) plays a catalytic role in tRNA translocation and a facilitative role in ribosome recycling. By stabilizing the rotated ribosome and interacting with ribosome recycling factor (RRF), EF-G was hypothesized to induce the domain rotations of RRF, which subsequently performs the function of splitting the major intersubunit bridges and thus separates the ribosome into subunits for recycling. Here, with systematic mutagenesis, FRET analysis and cryo-EM single particle approach, we analyzed the interplay between EF-G/RRF and post termination complex (PoTC). Our data reveal that the two conserved loops (loop I and II) at the tip region of EF-G domain IV possess distinct roles in tRNA translocation and ribosome recycling. Specifically, loop II might be directly involved in disrupting the main intersubunit bridge B2a between helix 44 (h44 from the 30S subunit) and helix 69 (H69 from the 50S subunit) in PoTC. Therefore, our data suggest a new ribosome recycling mechanism which requires an active involvement of EF-G. In addition to supporting RRF, EF-G plays an enzymatic role in destabilizing B2a via its loop II.
authors.affiliation: Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Dejiu
authors.initials: D
authors.lastname: Zhang
authors.affiliation: Ministry of Education Key Laboratory of Protein Sciences, Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China.
authors.forename: Kaige
authors.initials: K
authors.lastname: Yan
authors.affiliation: Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China College of Life Sciences, Nankai University, Tianjin 300071, China.
authors.forename: Yiwei
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Guangqiao
authors.initials: G
authors.lastname: Liu
authors.affiliation: Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Xintao
authors.initials: X
authors.lastname: Cao
authors.affiliation: Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Guangtao
authors.initials: G
authors.lastname: Song
authors.affiliation: College of Life Sciences, Nankai University, Tianjin 300071, China qiangxie@nankai.edu.cn.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Xie
authors.affiliation: Ministry of Education Key Laboratory of Protein Sciences, Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China ninggao@tsinghua.edu.cn.
authors.forename: Ning
authors.initials: N
authors.lastname: Gao
authors.affiliation: Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China University of Chinese Academy of Sciences, Beijing 100049, China qiny@ibp.ac.cn.
authors.forename: Yan
authors.initials: Y
authors.lastname: Qin
mesh_terms: D020285:Cryoelectron Microscopy; D009154:Mutation; D020653:Peptide Elongation Factor G / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D014176:Protein Biosynthesis; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000378:metabolism; D012343:RNA, Transfer / Q000378:metabolism; D012269:Ribosomal Proteins / Q000378:metabolism; D012270:Ribosomes / Q000737:chemistry* / Q000378:metabolism
chemical_list: D020653:Peptide Elongation Factor G; D012333:RNA, Messenger; D012269:Ribosomal Proteins; C087267:ribosome releasing factor; D012343:RNA, Transfer