Assembly of human translational elongation factor 1B is based on the interaction of the glutathione transferase‐like domains from alpha and gamma subunits

Abstract

In the process of human translational elongation, eEF1A·GDP is exchanged to eEF1A·GTP by eEF1B, which consists of three subunits, α, β, and γ. Among them, α and β subunits have guanidine exchange function while eEF1Bγ can bind to both α and β subunits. The N‐terminal GST domain of eEF1Bγ is responsible for the interaction to the N‐terminal regions of eEF1Bα and β. We obtained the 2:2 complex of the N‐terminal eEF1Bα and γ domains, and determined the crystal structure of the complex at the resolution of 2.1 Å. eEF1Bγ has a canonical GST domain consisted GST‐N containing a four stranded β‐sheet and helical GST‐C subdomains while the N‐terminal region of the eEF1Bα forms a GST‐C subdomain. The tetrameric complex has an order of α‐γ‐γ‐α subunits. The interaction between γ and γ subunits is similar to that of canonical GST dimer. however, the interaction between α and γ subunits is using their GST‐C domains. Binding assay with α and γ subunits containing mutations at the binding interfaces confirmed the interfaces for α‐γ and γ‐γ subunit interactions. Although the N‐terminal domains of eEF1Bα and eEF1Bγ form a heterotetramer, gel filtration analysis of the full‐length complex indicate their 4:4 complex suggesting another interactions through other regions than the N‐terminal domains. Furthermore, these two subunits could form even a bigger complex (8:8:8) in the presence of eEF1Bβ subunit.Support or Funding InformationKNU Creative BioResearch Group, School of Life Sciences and Biotechnology, Kyungpook National University, Daegu 702‐701, Korea