Interaction of phosphorylated elongation factor EF‐2 with nucleotides and ribosomes

FEBS Letters

Sontag, Bruno¹  Guillot, Dominique¹  Dumont-Miscopein, Agnès¹  Reboud, Jean-Paul¹  Lavergne, Jean-Pierre¹ 

[1] Laboratoire de Biochimie Médicale, Institut de Biologie et Chimie des Protéines, UPR CNRS 412, 7, Passage du Vercors - 69367 Lyon Cedex 07, France

关键词: Elongation factor EF-2;    Phosphorylation;    Guanylic nucleotide;    Fluorescence;   

DOI  :  10.1016/0014-5793(94)01272-5

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The intrinsic fluorescence emission spectrum of elongation factor EF-2 due to the 7 Trp residues was not modified after complete phosphorylation of the factor by the specific Ca²⁺/Calmodulin-dependent kinase III. The effect of nucleotide binding on this fluorescence revealed differences between phosphorylated and unmodified EF-2. Low concentrations of GTP had a smaller quenching effect on the fluorescence of phosphorylated EF-2 than on the fluorescence of unmodified EF-2, whereas GDP had exactly the same quenching effect on the fluorescence of both samples. These results suggest that phosphorylation of EF-2 decreased its affinity for GTP but not for GDP. Ability of phosphorylated EF-2 to form a ternary complex with ribosomes in the presence of a non-hydrolysable GTP analog and its ability to protect ribosomes against ricin-inactivation were both decreased to the same extent. The lower affinity of phosphorylated EF-2 for GTP could be responsible for a weaker and/or incorrect interaction of the factor with the ribosome, in particular with the ricin-site of the 28-S rRNA assumed to be involved in translocation initiation.

【 授权许可】

Unknown