Functional characterization of the DnaK chaperone system from the archaeon Methanothermobacter thermautotrophicusΔH

We characterized the biochemical and functional properties of the DnaK system from the archaeon Methanothermobacter thermautotrophicus ΔH. In contrast to the eubacterial chaperone components the archaeal Hsp70 system shows thermal transitions only slightly above the optimal environmental temperature (65 °C). Nevertheless, it prevents aggregation of luciferase in the physiological temperature range of the organism, but is also fully functional at 30 °C in luciferase refolding. Additionally, GrpEM.th. and DnaJM.th. substitute their eubacterial counterparts whereas DnaKM.th. is only functional with its native cochaperones which could be attributed to a functional specialization of the eubacterial chaperones during evolution.