The Arabidopsis Translation factor eEF1Bγ impacts plant development and associates with heat-induced cytoplasmic foci.

The important role of translational control for maintenance of proteostasis is well documented in plants, but the exact mechanisms that coordinate translation rates during plant development and stress response are not well understood. In Arabidopsis, the translation elongation complex eEF1B consists of three subunits: eEF1Bα, eEF1Bβ and eEF1Bγ. While eEF1Bα and eEF1Bβ have a conserved GDP/GTP exchange function, the function of eEF1Bγ is still unknown. By generating Arabidopsis mutants with strongly reduced eEf1Bγ levels, we revealed its essential role during plant growth and development and analysed its impact on translation. To explore the function of the eEF1B subunits at high temperature stress, we analysed their dynamic localisation as GFP-fusions under control and heat stress conditions. Each of these fusion proteins accumulated in heat-induced cytoplasmic foci and co-localised with the stress-granule marker PAB8-mCherry. Protein-protein-interaction studies and co-expression analyses indicated that eEF1Bβ physically interacted with both other subunits and promoted their recruitment to cytoplasmic foci. These data provide new insights into the mechanisms allowing for rapid adaption of translation rates during heat stress response.