title: Nascent peptide side chains induce rearrangements in distinct locations of the ribosomal tunnel.
abstract: Although we have numerous structures of ribosomes, none disclose side-chain rearrangements of the nascent peptide during chain elongation. This study reports for the first time that rearrangement of the peptide and/or tunnel occurs in distinct regions of the tunnel and is directed by the unique primary sequence of each nascent peptide. In the tunnel mid-region, the accessibility of an introduced cysteine to a series of novel hydrophilic maleimide reagents increases with increasing volume of the adjacent chain residue, a sensitivity not manifest at the constriction and exit port. This surprising result reveals molecular movements not yet resolvable from structural studies. These findings map solvent-accessible volumes along the tunnel and provide novel insights critical to our understanding of allosteric communication within the ribosomal tunnel, translational arrest, chaperone interaction, folding, and rates of elongation.
authors.affiliation: Department of Physiology, University of Pennsylvania, PA 19104, USA.
authors.forename: Jianli
authors.initials: J
authors.lastname: Lu
authors.forename: Zhengmao
authors.initials: Z
authors.lastname: Hua
authors.forename: William R
authors.initials: WR
authors.lastname: Kobertz
authors.forename: Carol
authors.initials: C
authors.lastname: Deutsch
mesh_terms: D003545:Cysteine / Q000378:metabolism; D010441:Peptide Chain Elongation, Translational; D010455:Peptides / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D012269:Ribosomal Proteins / Q000737:chemistry / Q000378:metabolism*; D012270:Ribosomes / Q000737:chemistry / Q000378:metabolism*
chemical_list: D010455:Peptides; D012269:Ribosomal Proteins; D003545:Cysteine