The unique chaperone operon of Thermotoga maritima: cloning and initial characterization of a functional Hsp70 and small heat shock protein.

The hyperthermophilic eubacterium Thermotoga maritima possesses an operon encoding an Hsp70 molecular chaperone protein and a protein with meaningful homology to the small heat shock protein family of chaperones. This represents the first demonstrated co-operon organization for these two important classes of molecular chaperones. We have cloned and initially characterized these proteins as functional chaperones in vitro: the Hsp70 is capable of ATP hydrolysis and substrate binding, and the small heat shock protein can suppress protein aggregation and stably bind a refolding-competent substrate. In addition, the primary sequence of the Hsp70 is used to infer the phylogenetic relationships of T. maritima, one of the deepest-branching eubacteria known.