Development and Application of Chaperone Peptide

Abstract

Molecular chaperones suppress the protein aggregation to assist the protein folding. In this study, we have investigated the application of the chaperone peptide, derived from the substrate binding site of the molecular chaperone αA-crystallin. αA-crystallin is one of the major structural proteins within the eye lens, and exhibits chaperone-lik e activity to be involved in the maintenance of the lens transparency. Former study has shown that a synthetic peptide KFVIFLDVKHFSPEDLTVK, which corresponds to the residues 70-75 of αA-crystallin exhibited the chaperone-like activity [K. K. Sharma, et al. J. Biol. Chem., 275, 3767 (2000)]. In addition, the chaperone-like activity was improved by the K70D substitution in this peptide (mini-αA-crystallin). We have constructed an expression vector for the luciferase joined with mini-αA-crystallin by PCR technique, and the chimerical luciferase was produced by in vitro protein expression system PROTEIOS (TOYOBO). However, the expression efficiency and the thermal stability of the chimerical lucifrease were not improved compared with wild type luciferase. Alternatively, we immobilized mini-αA-crystallin on the surface of the nano-particle using affinity tag, and examined the effect on the amyloid fibril formation, which causes the neurodegenerative disorder. The chaperon-like activity of mini-αA-crystallin was significantly improved by the immobilization on the nano-particle, suggesting that it would be applicable for various fields including the protein engineering and medicine.