Chaperone properties of bacterial elongation factor EF-Tu.
Elongation factor Tu (EF-Tu) is involved in the binding and transport of the appropriate codon-specified aminoacyl-tRNA to the aminoacyl site of the ribosome. We report herewith that the Escherichia coli EF-Tu interacts with unfolded and denatured proteins as do molecular chaperones that are involved in protein folding and protein renaturation after stress. EF-Tu promotes the functional folding of citrate synthase and alpha-glucosidase after urea denaturation. It prevents the aggregation of citrate synthase under heat shock conditions, and it forms stable complexes with several unfolded proteins such as reduced carboxymethyl alpha-lactalbumin and unfolded bovine pancreatic trypsin inhibitor. The EF-Tu.GDP complex is much more active than EF-Tu.GTP in stimulating protein renaturation. These chaperone-like functions of EF-Tu occur at concentrations that are at least 20-fold lower than the cellular concentration of this factor. These results suggest that EF-Tu, in addition to its function in translation elongation, might be implicated in protein folding and protection from stress.
Caldas
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TD
Biochimie Génétique, Institut Jacques Monod, Université Paris 7, 2 place Jussieu, 75005 Paris, France.
El Yaagoubi
A
A
Richarme
G
G
D002950:Citrate (si)-Synthase / Q000648:ultrastructure; D004926:Escherichia coli; D020963:GTP Phosphohydrolase-Linked Elongation Factors / Q000502:physiology; D006358:Hot Temperature; D018832:Molecular Chaperones; D010444:Peptide Elongation Factor Tu / Q000502:physiology*; D011485:Protein Binding; D011489:Protein Denaturation; D017510:Protein Folding; D000520:alpha-Glucosidases / Q000648:ultrastructure
D018832:Molecular Chaperones; D002950:Citrate (si)-Synthase; D000520:alpha-Glucosidases; D020963:GTP Phosphohydrolase-Linked Elongation Factors; D010444:Peptide Elongation Factor Tu