title: Visualizing tmRNA entry into a stalled ribosome.
abstract: Bacterial ribosomes stalled on defective messenger RNAs (mRNAs) are rescued by tmRNA, an approximately 300-nucleotide-long molecule that functions as both transfer RNA (tRNA) and mRNA. Translation then switches from the defective message to a short open reading frame on tmRNA that tags the defective nascent peptide chain for degradation. However, the mechanism by which tmRNA can enter and move through the ribosome is unknown. We present a cryo-electron microscopy study at approximately 13 to 15 angstroms of the entry of tmRNA into the ribosome. The structure reveals how tmRNA could move through the ribosome despite its complicated topology and also suggests roles for proteins S1 and SmpB in the function of tmRNA.
authors.affiliation: Howard Hughes Medical Institute, Wadsworth Center, Health Research, Inc., Empire State Plaza, Albany, NY 12201-0509, USA.
authors.forename: Mikel
authors.initials: M
authors.lastname: Valle
authors.forename: Reynald
authors.initials: R
authors.lastname: Gillet
authors.forename: Sukhjit
authors.initials: S
authors.lastname: Kaur
authors.forename: Anke
authors.initials: A
authors.lastname: Henne
authors.forename: V
authors.initials: V
authors.lastname: Ramakrishnan
authors.forename: Joachim
authors.initials: J
authors.lastname: Frank
mesh_terms: D000409:Alanine; D000926:Anticodon; D001426:Bacterial Proteins / Q000378:metabolism; D003062:Codon; D018388:Codon, Terminator; D020285:Cryoelectron Microscopy; D006160:Guanosine Triphosphate / Q000378:metabolism; D007091:Image Processing, Computer-Assisted; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D016366:Open Reading Frames; D010444:Peptide Elongation Factor Tu / Q000378:metabolism; D014176:Protein Biosynthesis; D011728:Pyridones / Q000494:pharmacology; D012329:RNA, Bacterial / Q000737:chemistry* / Q000378:metabolism*; D012333:RNA, Messenger / Q000737:chemistry / Q000378:metabolism; D012343:RNA, Transfer / Q000737:chemistry / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism; D012269:Ribosomal Proteins / Q000737:chemistry / Q000378:metabolism; D012270:Ribosomes / Q000378:metabolism*; D016963:Thermus thermophilus / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D000926:Anticodon; D001426:Bacterial Proteins; D003062:Codon; D018388:Codon, Terminator; D011728:Pyridones; D012329:RNA, Bacterial; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D012269:Ribosomal Proteins; C015494:ribosomal protein S1; C430328:small protein B; C096222:tmRNA; D006160:Guanosine Triphosphate; D012343:RNA, Transfer; D010444:Peptide Elongation Factor Tu; D000409:Alanine; C008536:mocimycin