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Structure of tmRNA-(SmpB)2 complex as inferred from cryo-EM

Overview

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.

About this Structure

2OB7 is a Protein complex structure of sequences from Thermus thermophilus. Full crystallographic information is available from OCA.

Reference

Scaffolding as an organizing principle in trans-translation. The roles of small protein B and ribosomal protein S1., Gillet R, Kaur S, Li W, Hallier M, Felden B, Frank J, J Biol Chem. 2007 Mar 2;282(9):6356-63. Epub 2006 Dec 19. PMID:17179154

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