Diphthamide synthesis is linked to the eEF2-client chaperone machinery.

Area of Science:

• Molecular Biology
• Cell Biology
• Biochemistry

Background:

• The diphthamide modification of eukaryotic translation elongation factor 2 (eEF2) is vital for accurate protein synthesis.
• While enzymes responsible for diphthamide synthesis are identified, the coordination between eEF2 synthesis and its modification remains unclear.

Purpose of the Study:

• To investigate the coordination of eEF2 synthesis and diphthamide modification.
• To identify factors involved in ensuring only modified eEF2 is maintained.

Main Methods:

• Analysis of physical and genetic interactions from the BioGRID database in yeast.
• Examination of eEF2 modification in deletion strains of Hsp90 co-chaperones (Hgh1 and Cpr7).

Main Results:

• Physical and genetic interactions link diphthamide synthesis enzymes with chaperones, including Hsp90 co-chaperones Hgh1 and Cpr7.
• Deletion of Hgh1 or Cpr7 resulted in eEF2 lacking the diphthamide modification.
• Defects in other co-chaperones did not affect eEF2 diphthamide modification.

Conclusions:

• Diphthamide synthesis requires not only Dph enzymes but also eEF2-interacting co-chaperones Hgh1 and Cpr7.
• The process likely necessitates a specific conformational state of eEF2 maintained by particular chaperones.