Independent binding sites of small protein B onto transfer-messenger RNA during trans-translation.
Stalled bacterial ribosomes are freed by transfer-messenger RNA (tmRNA). With the help of small protein B (SmpB), protein synthesis restarts and tmRNA adds a tag to the stalled protein for destruction. The conformation of a 347 nt long tmRNA from a thermophile and its interactions with SmpB were monitored using structural probes. The RNA is highly folded, including the reading frame, with <30% of unpaired residues. Footprints between SmpB and tmRNA are in the elbow of the tRNA domain, in some pseudoknots including one essential for function and in the lower part of the stem exiting the tRNA domain. The footprints outside the tRNA domain are scattered onto the tmRNA sequence, but form a cluster onto its tertiary structure derived from cryo-EM data. Some footprints flank the first triplet to be translated in tmRNA, suggesting that SmpB participates in the insertion of the tmRNA-encoded reading frame into the decoding center. To discriminate between a conformational rearrangement of tmRNA and independent binding sites, surface plasmon resonance was used and has identified three independent binding sites of SmpB on the RNA, including the site on the tRNA domain. Accordingly, SmpB is proposed to move on the tmRNA scaffold during trans-translation.
Metzinger
Laurent
L
Université de Rennes I, UPRES JE 2311, Inserm ESPRI, Biochimie Pharmaceutique 2 Avenue du Prof. Léon Bernard, 35043 Rennes, France.
Hallier
Marc
M
Felden
Brice
B
D001483:Base Sequence; D001665:Binding Sites; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D014176:Protein Biosynthesis; D012329:RNA, Bacterial / Q000737:chemistry* / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000378:metabolism*; D017423:Sequence Analysis, RNA; D014158:Transcription, Genetic; D046249:Transfer RNA Aminoacylation
D012329:RNA, Bacterial; D016601:RNA-Binding Proteins; C430328:small protein B; C096222:tmRNA