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Phage P22 tailspike is a thermostable homotrimeric protein, and temperature-sensitive folding (tsf) and global suppressor mutations affect its folding yields at elevated temperatures. We earlier suggested that the folding of the tailspike protein in Escherichia coli requires an unidentified molecular chaperone. Accordingly, in the present study, the interactions of purified DnaK, DnaJ, and GrpE heat-shock proteins with the tailspike protein were investigated during the translation and folding of the protein. The cotranslational addition of DnaJ to the tailspike protein resulted in the arrest of folding, when Dnak and GrpE were missing. However, the presence of DnaK, DnaJ, and GrpE had no effect on the folding yield of the tailspike protein, thus, providing evidence for the binding of the nascent tailspike protein with DnaJ protein, a member of DnaK chaperoning cycle.
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