The pathway to GTPase activation of elongation factor SelB on the ribosome.
Nature
; 540(7631): 80-85, 2016 12 01.
Article
in En
| MEDLINE
| ID: mdl-27842381
ABSTRACT
In all domains of life, selenocysteine (Sec) is delivered to the ribosome by selenocysteine-specific tRNA (tRNASec) with the help of a specialized translation factor, SelB in bacteria. Sec-tRNASec recodes a UGA stop codon next to a downstream mRNA stem-loop. Here we present the structures of six intermediates on the pathway of UGA recoding in Escherichia coli by single-particle cryo-electron microscopy. The structures explain the specificity of Sec-tRNASec binding by SelB and show large-scale rearrangements of Sec-tRNASec. Upon initial binding of SelB-Sec-tRNASec to the ribosome and codon reading, the 30S subunit adopts an open conformation with Sec-tRNASec covering the sarcin-ricin loop (SRL) on the 50S subunit. Subsequent codon recognition results in a local closure of the decoding site, which moves Sec-tRNASec away from the SRL and triggers a global closure of the 30S subunit shoulder domain. As a consequence, SelB docks on the SRL, activating the GTPase of SelB. These results reveal how codon recognition triggers GTPase activation in translational GTPases.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Ribosomes
/
Bacterial Proteins
/
Escherichia coli
/
GTP Phosphohydrolases
Type of study:
Prognostic_studies
Language:
En
Journal:
Nature
Year:
2016
Document type:
Article
Affiliation country: