title: Common chaperone activity in the G-domain of trGTPase protects L11-L12 interaction on the ribosome.
abstract: Translational GTPases (trGTPases) regulate all phases of protein synthesis. An early event in the interaction of a trGTPase with the ribosome is the contact of the G-domain with the C-terminal domain (CTD) of ribosomal protein L12 (L12-CTD) and subsequently interacts with the N-terminal domain of L11 (L11-NTD). However, the structural and functional relationships between L12-CTD and L11-NTD remain unclear. Here, we performed mutagenesis, biochemical and structural studies to identify the interactions between L11-NTD and L12-CTD. Mutagenesis of conserved residues in the interaction site revealed their role in the docking of trGTPases. During docking, loop62 of L11-NTD protrudes into a cleft in L12-CTD, leading to an open conformation of this domain and exposure of hydrophobic core. This unfavorable situation for L12-CTD stability is resolved by a chaperone-like activity of the contacting G-domain. Our results suggest that all trGTPases-regardless of their different specific functions-use a common mechanism for stabilizing the L11-NTD•L12-CTD interactions.
authors.affiliation: Laboratory of Noncoding RNA, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China.
authors.forename: Dandan
authors.initials: D
authors.lastname: Zhang
authors.forename: Guangqiao
authors.initials: G
authors.lastname: Liu
authors.forename: Jiaying
authors.initials: J
authors.lastname: Xue
authors.forename: Jizhong
authors.initials: J
authors.lastname: Lou
authors.forename: Knud H
authors.initials: KH
authors.lastname: Nierhaus
authors.forename: Weimin
authors.initials: W
authors.lastname: Gong
authors.forename: Yan
authors.initials: Y
authors.lastname: Qin
mesh_terms: D004926:Escherichia coli / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000378:metabolism; D020963:GTP Phosphohydrolase-Linked Elongation Factors / Q000737:chemistry / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000737:chemistry* / Q000378:metabolism; D057927:Hydrophobic and Hydrophilic Interactions; D008958:Models, Molecular; D018832:Molecular Chaperones / Q000737:chemistry* / Q000378:metabolism; D020653:Peptide Elongation Factor G / Q000737:chemistry / Q000378:metabolism; D010448:Peptide Initiation Factors; D054730:Protein Interaction Domains and Motifs; D012269:Ribosomal Proteins / Q000737:chemistry* / Q000378:metabolism; D012270:Ribosomes / Q000378:metabolism; D055672:Static Electricity; D035602:Transcriptional Elongation Factors / Q000737:chemistry / Q000378:metabolism
chemical_list: D029968:Escherichia coli Proteins; C515651:LepA protein, E coli; D018832:Molecular Chaperones; D020653:Peptide Elongation Factor G; D010448:Peptide Initiation Factors; D012269:Ribosomal Proteins; D035602:Transcriptional Elongation Factors; C027624:ribosomal protein L11; C525862:rplK protein, E coli; C512844:rplL protein, E coli; D020963:GTP Phosphohydrolase-Linked Elongation Factors; D019204:GTP-Binding Proteins