INTERACTION OF THE TRANSIT PEPTIDE OF A CHLOROPLAST PRECURSOR PROTEIN WITH HSP100 CHAPERONES

BRUCH, E. M.; CECCARELLI, E. A.

Mar del Plata, Buenos Aires

Congreso; XLIII Reunión Anual de la Sociedad Argentina de investigación en Bioquímica y Biología Molecular (SAIB); 2007

Sociedad Argentina de investigación en Bioquímica y Biología Molecular

Transit peptides (TP) are N-terminal extensions that route nuclearencoded proteins into plastids. Although Hsp100 chaperones havebeen implicated in precursor import into plastids, evidences ofHsp100-TP interaction are lacking. We have analyzed theinteraction between the TP of pea ferredoxin NADP+ reductase(FNR) and several Hsp100 chaperones from and .Four plasmids were constructed for the expression of FNR, FNRprecursor (preFNR), GFP and an amino terminal TP fusion to GFP(TP-GFP). We also constructed two plasmid for the expression oftwo Hsp100 chaperones ClpC1 and ClpC2 from . In vivofluorescence plates, protein accumulation in soluble fractionsand protein aggregation into inclusion bodies were analyzed usingseveral comparative assays. Ours results show that mutantsdefective in Hsp100 contained more aggregated TP-GFP andpreFNR than the wild type strains. Co-expression of TP-GFP orpreFNR and chaperones resulted in a reduction ofaggregates. Controls expressing GFP and FNR showed nosignificant differences between wild type and Hsp100-defective. These results indicate that the TP directs the fusion proteins todegradation, in which Hsp100s are involved. We suggest that thiseffect is produced by an interaction between the FNR TP andHsp100s from and Hsp100s from E. coli A. Thaliana