Natural chaperonin of the hyperthermophilic archaeum, Thermococcus strain KS-1:: a hetero-oligomeric chaperonin with variable subunit composition

To study the difference in expression of the chaperonin alpha- and beta -subunits in Thermococcus strain KS-1 (T. KS-1), we measured their intracellular contents at various growth temperatures using subunit-specific antibodies. The beta -subunit was significantly more abundant with increasing temperature (maximum at 93 degreesC), whereas the alpha -subunit was not. Native PAGE with Western blot analysis indicated that the natural chaperonins in the crude extracts of T. KS-1 cells grown between 65 degreesC and 95 degreesC migrate as single bands with different mobility. The recombinant alpha- and beta -subunit homo-oligomers migrated differently from each other and from natural chaperonins. Immunoprecipitation also showed that the natural chaperonin was the hetero-oligomer. These results indicate that chaperonin in T. KS-1 formed a hetero-oligomer with variable subunit composition, and that the beta -subunit may be adapted to a higher temperature than the alpha -subunit. T. KS-1 probably changes its chaperonin subunit composition to acclimatize to the ambient temperature.