Thermal Stability of Thermoanaerobacter tengcongensis Ribosome Recycling Factor

Ribosome recycling factor (RRF) and elongation factor-G catalyze disassembly of the post-termination complex and recycling of the ribosomal subunits back to a new round of initiation. Thermoanaerobacter tengcongensis survive high temperatures that Escherichia coli cannot, partly due to the higher thermal stability of T. tengcongensis ribosome recycling factor (tteRRF). Here we compared the structural stability of tteRRF and E. coli RRF (ecoRRF) and explore the reasons for the differences. We obtained the values of the thermodynamic parameters. Salt could reduce the thermal stability of tteRRF, which suggested that ion pairing was an important stabilizing factor in the case of tteRRF. The value of the heat capacity change of tteRRF unfolding, δCp, is significantly smaller than that of ecoRRF. A consequence of the small δCp value is that the change in free energy upon unfolding (δG) of tteRRF is larger than that of ecoRRF, while the values of the enthalpy change (δH) and the entropy change multiplied by temperature (T*δS) are smaller. The small δCp of tteRRF appears to be the main stabilizing factor for tteRRF.