Insights Into The Hsp100-Transite Peptide Recognition Process

BRUCH, E. M.; ROSANO, G. L.; CECCARELLI, E. A.

Puerto Madryn

Congreso; XLVI Reunión Anual Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2010

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

Molecular chaperones of the Hsp100 family have been identified inall kingdoms of life. It has been proposed that these proteins play akey role in protein folding assistance, disaggregation, proteolysisand precursor import into chloroplasts. Some of these activities havebeen previously observed investigating an Hsp100 form E. colicalled ClpA. However, the role of Hsp100 in chloroplast import hasnot been elucidated. It has been postulated that a crucial step inprotein translocation into plastids requires the binding of an Hsp100to an amino-terminal region of the protein called transit peptide(TP). However, evidences of Hsp100-TP interaction are lacking.The goal of this work is to demonstrate this interaction and gainfurther insight into its nature, using the TP of pea ferredoxin NADP+reductase (FNR) as a model and two Hsp100 chaperons from A.thaliana ( ClpC2 and ClpD). TP fused to the GST N-terminusinteracts with both plant chaperones. On the contrary, fusions inwhich the TP was placed at the carboy-terminus of GST or betweenGST and FNR were not recognized by the chaperones. Moreover,evidences were obtained indicating that interaction with the fulltransit peptide was lower than a shorter version of this peptide. Ourresults show for the first time in vitro evidence for the interactionbetween a TP and an Hsp100 from A. Thaliana.