Lukash T. Chaperone-like properties of translational components from higher eukaryotes

The experimental evidences of chaperone-like properties of 80S ribosomes and translation elongation factor 1A (eEF1A) are presented. The efficient stimulation of partly inactivated leucyl-, isoleucyl- and phenylalanyl-tRNA synthetases and protection of phenylalanyl-tRNA synthetase against the heat inactivation at 42 C indicate the refolding and stabilizing capacity of the ribosomes. eEF1A is capable to recover the activity of heat inactivated phenylalanyl- and seryl-tRNA synthetase and maintain the activity of phenylalanyl-tRNA synthetase under heat chock conditions. Structural changes in the phenylalanyl-tRNA synthetase molecules after heat inactivation, determined by the circular dichroism, dynamic light scattering and non-denaturing agarose electrophoresis, comprise change in the total surface charge, protein aggregation and 20 % decrease in a- helical structure. eEF1A is shown to restore the total surface charge of phenylalanyl-tRNA synthetase and reduce the level of aggregation similar to molecular chaperones. Chaperon-like capacity of 80S ribosomes and eEF1A might be important for maintaining the active conformations of the protein synthesis components in the translation compartments during consecutive elongation cycles.