title: Ribosomal proteins S12 and S13 function as control elements for translocation of the mRNA:tRNA complex.
abstract: Translocation of the mRNA:tRNA complex through the ribosome is promoted by elongation factor G (EF-G) during the translation cycle. Previous studies established that modification of ribosomal proteins with thiol-specific reagents promotes this event in the absence of EF-G. Here we identify two small subunit interface proteins S12 and S13 that are essential for maintenance of a pretranslocation state. Omission of these proteins using in vitro reconstitution procedures yields ribosomal particles that translate in the absence of enzymatic factors. Conversely, replacement of cysteine residues in these two proteins yields ribosomal particles that are refractive to stimulation with thiol-modifying reagents. These data support a model where S12 and S13 function as control elements for the more ancient rRNA- and tRNA-driven movements of translocation.
authors.affiliation: Howard Hughes Medical Institute, Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
authors.forename: Anthony R
authors.initials: AR
authors.lastname: Cukras
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Southworth
authors.forename: Julie L
authors.initials: JL
authors.lastname: Brunelle
authors.forename: Gloria M
authors.initials: GM
authors.lastname: Culver
authors.forename: Rachel
authors.initials: R
authors.lastname: Green
mesh_terms: D001692:Biological Transport; D003545:Cysteine / Q000737:chemistry; D004926:Escherichia coli / Q000378:metabolism; D029968:Escherichia coli Proteins; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D020653:Peptide Elongation Factor G / Q000378:metabolism; D010649:Phenylalanine / Q000737:chemistry; D011485:Protein Binding; D017433:Protein Structure, Secondary; D012333:RNA, Messenger / Q000378:metabolism*; D012343:RNA, Transfer / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D012269:Ribosomal Proteins / Q000737:chemistry*; D013997:Time Factors
chemical_list: D029968:Escherichia coli Proteins; D020653:Peptide Elongation Factor G; D012333:RNA, Messenger; D011994:Recombinant Proteins; D012269:Ribosomal Proteins; C034212:ribosomal protein S12; C040469:ribosomal protein S30; C512838:rpsM protein, E coli; D010649:Phenylalanine; D012343:RNA, Transfer; D003545:Cysteine