Analysis of Chaperone Function and Formation of Hetero-oligomeric Complexes of Hsp18.1 and Hsp17.7, Representing Two Different Cytoplasmic sHSP Classes in Pisum sativum |
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Authors: | Daniela Wagner Jens Schneider-Mergener Christoph Forreiter |
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Institution: | 2. Institut für Pflanzenwissenschaften, ETH Zürich, Universit?tstr. 2, Zürich, CH-8092, Switzerland 3. Institut für Medizinische Immunologie, Charité, Humboldt-Universit?t Berlin, Hessische Strasse 3-4, Berlin, D-10115, Germany 1. Department of Plant Physiology, Justus-Liebig University, Senckenbergstr. 3, Giessen, D-35390, Germany
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Abstract: | Small heat shock proteins (sHSPs) are the most abundant stress proteins in plants. Usually not expressed under permissive
conditions, they can accumulate to more than 2% of the total cellular protein content during heat stress. At present several
points of evidence indicate that these proteins act as molecular chaperones by keeping partially denatured proteins in a folding-competent
state. In plants sHSPs are encoded by a multigene family, which can be segregated into several classes according to their
subcellular position and/or sequence homology. Curiously, two different classes appear in the cytoplasm. Their specific role
during heat shock remains elusive. Here we present some evidence that both classes of sHSPs enhance recovery of reporter protein
activity in the presence of HSP70. Applying peptide arrays prepared by SPOT synthesis and in situ analysis by confocal laser scanning microscopy, we could further show that the two classes of sHSP are attached to each other
and are able to interact with non-native proteins both in vivo and in vitro. Although both of the sHSPs act similarly as molecular chaperones, immunohistochemistry experiments support the hypothesis
that the two have different cellular functions in the development of heat-induced cytoplasmic heat shock granules under elevated
temperatures.
Daniela Wagner Deceased 24 Feburary 2004. |
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Keywords: | SHSP Chaperone Plants |
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