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Role of Two Peroxisomal Small Heat Shock Proteins in Re-Naturating Oxidatively Damaged Proteins and Conferring Heat Resistance to Crop Plant

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2011 - 2012

Environmental stresses, such as drought, high salinity, extremes of temperature (high and low), can significantly alter plant metabolism, growth and development, ultimately leading to the severe loss of plant productivity. At the molecular level, these st resses lead to the misfolding and denaturation of proteins and to aberrant of not totally dysfunctional proteins and enzymes. The ubiquitously present heat shock proteins (Hsps) are a class of molecular chaperones that are expressed in response to increas ed temperature and other abiotic stresses and help in renaturation of denatured polypeptides. Among the cell organelles peroxisomes are important as they are the site where reactive oxygen species are produced during photosynthesis. Therefore, these organ elles are constantly prone to oxidative damage. Even though they have enzymes such as catalase to detoxify the ROS induced damage, still not much is known how the denatured or misfolded proteins are handled in peroxisomes. The Reumann group has shown that two of the small heat shock proteins (sHSPs) AtHsp15.7 and AtAcd31.2 are present in peroxisomes and are important for the survival of the organism at elevated temperatures. Small heat shock proteins (sHSPs) belong to a class of molecular chaperones that act to prevent the aggregation of misfolded proteins but lacks the ability to renature them into their proper conformation. Thus either they direct these proteins to proteases for degradation or to the other chaperones (such as Hsp70, Hsp90) that have the ability to refold them. Therefore, this study is aimed to find out the role of sHSPs present in plant peroxisomes in preventing the cells from oxidative damage. Since there is no report on the presence of heat shock proteins capable of ATP hydrolysis and renaturing the damaged proteins, this study also aims to find out the co-chaperons such as Hsp70/Hsp90 in the plant peroxisomes.