Modification of the reactivity of three amino-acid residues in elongation factor 2 during its binding to ribosomes and translocation.
The accessibility of three amino acids of EF-2, located within highly conserved regions near the N- and C-terminal extremities of the molecule (the E region and the ADPR region, respectively) to modifying enzymes has been compared within nucleotide-complexed EF-2 and ribosomal complexes that mimic the pre- and posttranslocational ones: the high-affinity complex (EF-2)-nonhydrolysable GTP analog GuoPP[CH2]P ribosome and the low-affinity (EF-2)-GDP-ribosome complex, EF-2 and ribosomes being from rat liver. We studied the reactivity of two highly conserved residues diphthamide-715 and Arg-66, to diphtheria-toxin-dependent ADP-ribosylation and trypsin attack, and of a threonine that probably lies between residues 51 and 60, to phosphorylation by a Ca2+/calmodulin-dependent protein kinase. Diphthamide 715 and this threonine residue were unreactive within the high-affinity complex but seemed fully reactive in the low-affinity complex. Arg-66 was resistant to trypsin in both complexes. The possible involvement of the E and ADPR regions of EF-2 in the interaction with ribosome in the two complexes is discussed.
Lavergne
J P
JP
Laboratoire de Biochimie Médicale, Université Claude Bernard, Villeurbanne, France.
Marzouki
A
A
Reboud
A M
AM
Reboud
J P
JP
D000246:Adenosine Diphosphate Ribose / Q000378:metabolism; D000818:Animals; D006150:Guanine Nucleotides / Q000378:metabolism; D006153:Guanosine Diphosphate / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000031:analogs & derivatives / Q000378:metabolism; D008099:Liver / Q000378:metabolism*; D009154:Mutation; D009243:NAD / Q000378:metabolism; D020652:Peptide Elongation Factor 2; D010445:Peptide Elongation Factors / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D010449:Peptide Mapping; D010750:Phosphoproteins / Q000235:genetics; D010766:Phosphorylation; D011485:Protein Binding; D051381:Rats; D012270:Ribosomes / Q000378:metabolism*; D014357:Trypsin
D006150:Guanine Nucleotides; D020652:Peptide Elongation Factor 2; D010445:Peptide Elongation Factors; D010750:Phosphoproteins; D009243:NAD; D006153:Guanosine Diphosphate; D000246:Adenosine Diphosphate Ribose; C004805:5'-guanylylmethylenebisphosphonate; D006160:Guanosine Triphosphate; D014357:Trypsin