Elongation factor complex interaction with ribosomes

Following dissociation from the ribosome the EF-Tu-GDP complex interacts with another elongation factor, EF-Ts, with formation of an EF-Tu-EF-Ts heterodimer and release of GDP. Reaction of the heterodimer with GTP regenerates the EF-Tu-GTP complex required for binding aminoacyl-tRNA. The sequence of events is similar in eukaryotes with eEF-lA (Mr 50,000) corresponding to EF-Tu and eEF-lB (Mr 30,000) to EF-Ts. 

The same method has been applied to measure the Eli domain orientation when the protein is in complex with its RNA parmer or both RNA and thiostrepton antibiotic. The additional RDCs revealed a rearrangement of the N-terminal domain of Ell placing it closer to the RNA after binding of thiostrepton. HADDOCK has been used to calculate a model of the ternary stmcture of the Ell protein in complex with RNA and antibiotic. Based on the orientational data, the dynamics and the docking model, it seems that thiostrepton locks the domain conformation of Ell in a rigid (inhibitory) state. The antibiotic thiostrepton interferes with the interaction of elongation factors to this Ell-RNA region, which has a dramatic effect on the level of protein synthesis by the ribosome. 

Elongation factors Non-ribosomal protein factors that are necessary participants in the chain-elongation cycle of polypeptide synthesis they interact with the ribosome-mRNA complex or with other major cycle participants. 

Addition of each incoming amino acid requires the cooperation of three elongation factors. Elongation factor Tu (EF-Tu) is the most abundant protein in E. coli, with about 100,000 copies per cell, or 5% of the cell s protein. This protein is a GTPase, and the EF-Tu GTP complex specifically binds aminoacyl-tRNAs (AA-tRNAs). Formation of the ternary complex (EF-Tu GTP AA-tRNA) protects the ester bond (linking the amino acid to its cognate tRNA) from hydrolysis, and transports the AA-tRNA to the ribosomal A-site. Once the correct codon-anticodon interaction is confirmed, ribosome-triggered hydrolysis of... 

---