The chloroplast HSP100/ClpB is a newly documented member of the ClpB family, but little was known about its role in imparting thermotolerance to cells. A cDNA coding for a HSP100/ClpB homolog has been cloned from Lycopersicon esculentum and termed as Lehsp100/ClpB (the cDNA sequence of Lehsp100/ClpB has been submitted to the GenBank database under accession number: AB219939). The protein encoded by the cDNA was most similar to the putative chloroplast HSP100/ClpBs in higher plants and the ClpB from Cyanobacterium Synechococcus sp. A 97 kDa protein, which matched the predicted size of mature LeHSP100/ClpB, was immunologically detected in chloroplast isolated from heat-treated tomato plants. In addition, the fusion protein, combining the transit sequence of LeHSP100/ClpB and GFP, was found to be located in chloroplast based on the observations of fluorescent microscope images. These results indicated the chloroplast-localization of LeHSP100/ClpB. Both the transcript and the protein of Lehsp100/ClpB were not detected under normal growth conditions, but they were induced by increasingly higher temperatures. An antisense Lehsp100/ClpB cDNA fragment was introduced into the tomato by Agrobacterium-mediated transformation. Antisense lines exhibited an extreme repression of heat-induced expression of Lehsp100/ClpB. The levels of chloroplast HSP60 and small HSP in antisense lines were identical to those of the control plants. After plants preconditioned at 38 degrees C for 2 h were exposed to a lethal heat shock at 46 degrees C for 2 h, the antisense lines were greatly impaired and withered in 21 days of the recovery phase, whereas the untransformed control plants and the vector-transformed plants survived. Furthermore, chlorophyll fluorescence measurements showed that PS II in antisense lines were more susceptible to the thermal irreversible inactivation than the untransformed and vector-transformed control plants. This work provides the first example that induction of chloroplast LeHSP100/ClpB contributes to the acquisition of thermotolerance in higher plants.
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| rdfs:comment |
The chloroplast HSP100/ClpB is a newly documented member of the ClpB family, but little was known about its role in imparting thermotolerance to cells. A cDNA coding for a HSP100/ClpB homolog has been cloned from Lycopersicon esculentum and termed as Lehsp100/ClpB (the cDNA sequence of Lehsp100/ClpB has been submitted to the GenBank database under accession number: AB219939). The protein encoded by the cDNA was most similar to the putative chloroplast HSP100/ClpBs in higher plants and the ClpB from Cyanobacterium Synechococcus sp. A 97 kDa protein, which matched the predicted size of mature LeHSP100/ClpB, was immunologically detected in chloroplast isolated from heat-treated tomato plants. In addition, the fusion protein, combining the transit sequence of LeHSP100/ClpB and GFP, was found to be located in chloroplast based on the observations of fluorescent microscope images. These results indicated the chloroplast-localization of LeHSP100/ClpB. Both the transcript and the protein of Lehsp100/ClpB were not detected under normal growth conditions, but they were induced by increasingly higher temperatures. An antisense Lehsp100/ClpB cDNA fragment was introduced into the tomato by Agrobacterium-mediated transformation. Antisense lines exhibited an extreme repression of heat-induced expression of Lehsp100/ClpB. The levels of chloroplast HSP60 and small HSP in antisense lines were identical to those of the control plants. After plants preconditioned at 38 degrees C for 2 h were exposed to a lethal heat shock at 46 degrees C for 2 h, the antisense lines were greatly impaired and withered in 21 days of the recovery phase, whereas the untransformed control plants and the vector-transformed plants survived. Furthermore, chlorophyll fluorescence measurements showed that PS II in antisense lines were more susceptible to the thermal irreversible inactivation than the untransformed and vector-transformed control plants. This work provides the first example that induction of chloroplast LeHSP100/ClpB contributes to the acquisition of thermotolerance in higher plants.
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| skos:exactMatch | |
| uniprot:name |
Plant Mol. Biol.
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| uniprot:author |
Li M.H.,
Liu J.,
Qin J.,
Sun A.Q.,
Sun Y.,
Yang J.Y.,
Yi S.Y.
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| uniprot:date |
2006
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| uniprot:pages |
385-395
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| uniprot:title |
The involvement of chloroplast HSP100/ClpB in the acquired thermotolerance in tomato.
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| uniprot:volume |
62
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| dc-term:identifier |
doi:10.1007/s11103-006-9027-9
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