Cooperation of the DnaK and GroE chaperone systems in the folding pathway of plant ferredoxin-NADP+ reductase expressed in Escherichia coli

DIONISI, H.; SUSANA KARINA CHECA; KRAPP, A. R.; ARAKAKI, A. K.; CECCARELLI, E. A.; CARRILLO, N. J.; VIALE, A. M.

EUROPEAN JOURNAL OF BIOCHEMISTRY

Blackwell Publishing Ltd

Lugar: England; Año: 1998 vol. 251 p. 724 - 728

0014-2956

The DnaK system is required for the productive folding of pea chloroplast ferredoxin-NADP1 reductase(FNR) expressed in Escherichia coli. The formation of a mature active enzyme was severely impairedin E. coli dnaK, dnaJ or grpE mutants expressing either the cytosolic precursor of the reductase (preFNR)or the mature apoenzyme, and these forms aggregated extensively in these cells. Coexpression of dnaKfrom a multicopy plasmid in the dnaK-null mutants restored preFNR processing and folding of FNR,rendering a mature-sized active enzyme. Overexpression of GroESL chaperonins failed to prevent preFNRaggregation, but it restored productive folding of FNR in dnaK-null mutants expressing the matureenzyme. Expression of preFNR in OmpT-protease-deficient E. coli cells resulted in the accumulation ofthe unprocessed precursor in the soluble fraction of the cells. The interaction of this soluble preFNR, butnot the mature reductase, with DnaK and GroEL was evidenced by immunoprecipitation studies. Weconclude that, in addition to the GroE chaperonins [Carrillo, N., Ceccarelli, E. A., Krapp, A. R., Boggio,S., Ferreyra, R. G. & Viale, A. M. (1992) J. Biol. Chem. 267, 15537215541], the DnaK chaperonesystem plays a crucial role in the folding pathway of FNR.