Format

Send to

Choose Destination
Mol Cell. 2007 Feb 23;25(4):519-29.

Kinetically competent intermediates in the translocation step of protein synthesis.

Author information

1
Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104, USA.

Abstract

Translocation requires large-scale movements of ribosome-bound tRNAs. Using tRNAs that are proflavin labeled and single-turnover rapid kinetics assays, we identify one or possibly two kinetically competent intermediates in translocation. EF-G.GTP binding to the pretranslocation (PRE) complex and GTP hydrolysis are rapidly followed by formation of the securely identified intermediate complex (INT), which is more slowly converted to the posttranslocation (POST) complex. Peptidyl tRNA within the INT complex occupies a hybrid site, which has a puromycin reactivity intermediate between those of the PRE and POST complexes. Thiostrepton and viomycin inhibit INT formation, whereas spectinomycin selectively inhibits INT disappearance. The effects of other translocation modulators suggest that EF-G-dependent GTP hydrolysis is more important for INT complex formation than for INT complex conversion to POST complex and that subtle changes in tRNA structure influence coupling of tRNA movement to EF-G.GTP-induced conformational changes.

PMID:
17317625
PMCID:
PMC1995019
DOI:
10.1016/j.molcel.2007.01.014
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for Elsevier Science Icon for PubMed Central
Loading ...
Support Center