OVERPRODUCTION OF DNAJ IN ESCHERICHIA-COLI IMPROVES IN-VIVO SOLUBILITY OF THE RECOMBINANT FISH-DERIVED TRANSGLUTAMINASE

The overexpression of red sea bream (Pagrus major) transglutaminase (T Gase, E.G. 2.3.2.13) in Escherichia coli mostly leads to the accumulat ion of biologically inactive enzyme. Although the solubility of the ge ne products could be improved by cultivation at a lower temperature (2 6-28 degrees C), most of the synthesized TGase was still in the form o f insoluble aggregates. The effects of overproduction of molecular cha perones on the intracellular solubility of newly produced recombinant TGase were examined. The overexpression of dnaK or groES/EL did not im prove solubility. However, DnaJ greatly increased the solubility of th e recombinant TGase, resulting in active enzyme in the presence of cal cium ions. Go-expression of dnaK along with dnaJ further increased the content of soluble TGase. Under our experimental conditions, suppleme ntation with both DnaJ and DnaK elevated the TGase activity in the pro ducer cells by roughly 4-fold, compared with the control strain cultur ed at 30 degrees C. Thus, we found that DnaJ is important in controlli ng the solubility of protein overproduced in E. coli.