Scaffolding as an organizing principle in trans-translation. The roles of small protein B and ribosomal protein S1.
A eubacterial ribosome stalled on a defective mRNA can be released through a quality control mechanism referred to as trans-translation, which depends on the coordinating binding actions of transfer-messenger RNA, small protein B, and ribosome protein S1. By means of cryo-electron microscopy, we obtained a map of the complex composed of a stalled ribosome and small protein B, which appears near the decoding center. This result suggests that, when lacking a codon, the A-site on the small subunit is a target for small protein B. To investigate the role of S1 played in trans-translation, we obtained a cryo-electron microscopic map, including a stalled ribosome, transfer-messenger RNA, and small protein Bs but in the absence of S1. In this complex, several connections between the 30 S subunit and transfer-messenger RNA that appear in the +S1 complex are no longer found. We propose the unifying concept of scaffolding for the roles of small protein B and S1 in binding of transfer-messenger RNA to the ribosome during trans-translation, and we infer a pathway of sequential binding events in the initial phase of trans-translation.
Gillet
Reynald
R
Université de Rennes I, IFR 140, UPRES JE 2311, INSERM U835 Biochimie Pharmaceutique, 2 Avenue du Professeur Léon Bernard, 35043 Rennes, France.
Kaur
Sukhjit
S
Li
Wen
W
Hallier
Marc
M
Felden
Brice
B
Frank
Joachim
J
D020285:Cryoelectron Microscopy; D046911:Macromolecular Substances / Q000378:metabolism*; D011485:Protein Binding; D014176:Protein Biosynthesis; D012343:RNA, Transfer / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000378:metabolism*; D012269:Ribosomal Proteins / Q000378:metabolism*; D016963:Thermus thermophilus / Q000235:genetics
D046911:Macromolecular Substances; D016601:RNA-Binding Proteins; D012269:Ribosomal Proteins; C015494:ribosomal protein S1; C430328:small protein B; D012343:RNA, Transfer