Specificity of elongation factor EF-TU for hydrophobic peptides.
The elongation factor EF-Tu carries aminoacyl-tRNAs to the A-site of the ribosome during the elongation process of protein biosynthesis. We, and others, have recently reported that the Escherichia coli EF-Tu interacts with unfolded and denatured proteins and behaves like a chaperone in protein folding and protection against protein thermal denaturation. In this study, we have identified EF-Tu binding sites in protein substrates by screening cellulose-bound peptides scanning the sequences of several proteins. The binding motifs recognized by EF-Tu in protein substrates are also recognized by the chaperone DnaK and mainly consist of hydrophobic clusters. EF-Tu interacts as efficiently as DnaK with the membrane spanning sequence of the membrane protein phospholemman and with the signal sequence of alkaline phosphatase. It interacts less efficiently with several other hydrophobic clusters of lysozyme and alkaline phosphatase, which are also DnaK substrates and fails to bind to several DnaK binding sites. Our results suggest that EF-Tu, like DnaK, interacts albeit more weakly with the hydrophobic regions of substrate protein and are consistent with the hypothesis that it possesses chaperone properties.
Malki
Abdelharim
A
Stress Molecules, Institut Jacques Monod, Université Paris 7, 2 place Jussieu, 75251 Paris Cedex 05, France.
Caldas
Teresa
T
Parmeggiani
Andrea
A
Kohiyama
Masamichi
M
Richarme
Gilbert
G
D000469:Alkaline Phosphatase / Q000378:metabolism; D000595:Amino Acid Sequence; D017122:Bacteriophage T4 / Q000201:enzymology; D001665:Binding Sites; D004792:Enzyme Precursors / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000378:metabolism*; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism; D057927:Hydrophobic and Hydrophilic Interactions; D008565:Membrane Proteins / Q000378:metabolism; D009113:Muramidase / Q000378:metabolism; D010444:Peptide Elongation Factor Tu / Q000378:metabolism*; D010455:Peptides / Q000737:chemistry* / Q000378:metabolism*; D010750:Phosphoproteins / Q000378:metabolism; D011485:Protein Binding; D013379:Substrate Specificity
D004792:Enzyme Precursors; D029968:Escherichia coli Proteins; D018840:HSP70 Heat-Shock Proteins; D008565:Membrane Proteins; D010455:Peptides; D010750:Phosphoproteins; C069141:phospholemman; D000469:Alkaline Phosphatase; D009113:Muramidase; D010444:Peptide Elongation Factor Tu; C063842:dnaK protein, E coli