Studies on the functions of chaperones participating cell morphology and on their relation with cell division

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Overexpression and purification of Bacillus thermoglucosidasius KP1006 DnaK. Overexpression of the DnaK protein was proformed using Escherichia coli cells as a host. Purified DanK proteins consisted of monomer and two to four identical oligomers. This was different fromt the observation for E.coli DanK protein that has a dimeric structure. ATPase activity of B.thermoglucosidasius DnaK gradually decreased as the purity increased. This suggested the activity might correlate with DanJ and GrpE proteins.Analyses of proteins that have an interaction with B.thermoglucosidasius DanK. The interaction of B.thermoglucosidasius DanK and E.coli FtsZ was investigated using a two-hybird system. The interaction between the two molecules was successfully detected. Furthermore, the functional region related to the interaction is being determined by constructing various chimeric plasmids of two molecules on the two-hybird vectors.B.thermoglucosidasius HrcA, a negative control repressor for chaperone expression. HrcA proteins can function by binding to the CIRCE (controlling inverted repeat of chaperon expression) element. However, this protein tends to aggregate under the non-denaturing conditions. So we attempted to solubilize B.thermoglucosidasius HrcA and eventually succeeded in it with DNA. Moreover, we found the complex of B.thermoglucosidasius HrcA and DNA is stable at a lower range of temperature (below 50℃) and denatured at elevated temperature. Therefore, we suggested that B.thermoglucosidasius HrcA should function as a thermosensor to initiate the gene expression of the groEL and danK operons.