Acquired Thermotolerance and Expression of the HSP100/ClpB Genes of Lima Bean

Keeler, Sharon J.; Boettger, Cynthia M.; Haynes, Janine G.; Kuches, Kelly Ann; Johnson, Mitzi M. S.; Thureen, Dean L.; Keeler, Calvin L.; Kitto, S.L.

doi:10.1104/pp.123.3.1121

Cited by 79 publications

(52 citation statements)

References 30 publications

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“…It is known that a nonlethal mild heat shock increases the thermotolerance of cells, and this is known as acquired thermotolerance (12,21). We examined whether Mx Hsp16.6 is involved in acquired thermotolerance.…”

Section: Vol 187 2005mentioning

confidence: 99%

Characterization of a Small Heat Shock Protein, Mx Hsp16.6, of Myxococcus xanthus

et al. 2005

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A number of heat shock proteins in Myxococcus xanthus were previously identified by two-dimensional (2D) gel electrophoresis. One of these protein was termed Mx Hsp16.6, and the gene encoding Mx Hsp16.6 was isolated. Mx Hsp16.6 consists of 147 amino acid residues and has an estimated molecular weight of 16,642, in accordance with the apparent molecular mass in the 2D gel. An ␣-crystallin domain, typically conserved in small heat shock proteins, was found in Mx Hsp16.6. Mx Hsp16.6 was not detected during normal vegetative growth but was immediately induced after heat shock. Expression of the hsp16.6 gene was not induced by other stresses, such as starvation, oxidation, and high osmolarity. Mx Hsp16.6 was mostly localized in particles formed after heat shock and precipitated by low-speed centrifugation. Furthermore, Mx Hsp16.6 was detected in highly electron-dense particles in heat-shocked cells by immunoelectron microscopy, suggesting that it forms large complexes with heat-denatured proteins. An insertion mutation in the hsp16.6 gene resulted in lower viability during heat shock and lower acquired thermotolerance. Therefore, it is likely that Mx Hsp16.6 plays critical roles in the heat shock response in M. xanthus.

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Section: Vol 187 2005mentioning

confidence: 99%

Characterization of a Small Heat Shock Protein, Mx Hsp16.6, of Myxococcus xanthus

et al. 2005

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“…In this analysis, cellular membrane damage due to heat stress was measured by the release of electrolytes from tissue into the surrounding solution. Electrolyte leakage analysis has been shown to be a reliable, quantitative and reproducible assay to represent thermotolerance in a variety of plants (Malik et al 1999;Keeler et al 2000), including potato (Chen, Shen & Li 1982;Coria et al 1998).…”

Section: Enhanced Cellular Membrane Stability In Transgenic Potato Plmentioning

confidence: 99%

Introduction of the carrot HSP17.7 into potato (Solanum tuberosum L.) enhances cellular membrane stability and tuberization in vitro

Ahn

Zimmerman

2005

Plant Cell & Environment

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We have examined the ability of a carrot (Daucus carota L.) heat shock protein gene encoding HSP17.7 (DcHSP17.7) to confer enhanced heat tolerance to potato (Solanum tuberosum L.), a cool‐season crop. The DcHSP17.7 gene was fused to a 6XHistidine (His) tag to distinguish the engineered protein from endogenous potato proteins and was introduced into the potato cultivar ‘Désirée’ under the control of the cauliflower mosaic virus (CaMV) 35S promoter. Western analysis showed that engineered DcHSP17.7 was constitutively, but not abundantly, expressed in transgenic potato lines before heat stress. Leaves from multiple regenerated potato lines that contain the transgene exhibited significantly improved cellular membrane stability at high temperatures, compared with wild‐type and vector control plants. Transgenic potato lines also exhibited enhanced tuberization in vitro: under a condition of constant heat stress, at 29 °C, nodal sections of the transgenic lines produced larger and heavier microtubers at higher rates, compared to the wild type and vector controls. The dry weight and percentages of microtubers that were longer than 5 mm were up to three times higher in the transgenic lines. Our results suggest that constitutive expression of carrot HSP17.7 can enhance thermotolerance in transgenic potato plants. To our knowledge, this is the first study that shows that the thermotolerance of potato can be enhanced through gene transfer.

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“…The main HSP of this chaperone family is ClpB, and most organisms produce at least two different types. Separate nuclear clpB genes in eukaryotes encode mitochondrial (78-kDa [11]) and cytosolic (100-to 110-kDa [19]) proteins, while plants have another ClpB isomer localized in chloroplasts (10). In contrast, a single gene in eubacteria encodes two differently sized proteins (ca.…”

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confidence: 99%

Novel Form of ClpB/HSP100 Protein in the Cyanobacterium Synechococcus

et al. 2001

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Synechococcus sp. strain PCC 7942 has a second clpB gene that encodes a 97-kDa protein with novel features. ClpBII is the first ClpB not induced by heat shock or other stresses; it is instead an essential, constitutive protein. ClpBII is unable to complement ClpBI function for acquired thermotolerance. No truncated ClpBII version is normally produced, unlike other bacterial forms, while ectopic synthesis of a putative truncated ClpBII dramatically decreased cell viability.In response to rising growth temperatures, all organisms synthesize heat shock proteins (HSPs). Many of these inducible polypeptides are members of larger families based on similar size and sequence homology, and most include proteins synthesized constitutively under nonstress conditions. Members of most HSP families function as molecular chaperones in assisting the folding, assembly, and translocation of other proteins during normal and adverse growth regimens. One relatively new family of chaperones is HSP100/Clp. It can be divided into two basic groups, with proteins in the first (ClpA to -E) having two distinct ATP-binding domains (ATP-1 and ATP-2) while proteins in the second (ClpX and -Y) possess only one such domain (21). The main HSP of this chaperone family is ClpB, and most organisms produce at least two different types. Separate nuclear clpB genes in eukaryotes encode mitochondrial (78-kDa [11]) and cytosolic (100-to 110-kDa [19]) proteins, while plants have another ClpB isomer localized in chloroplasts (10). In contrast, a single gene in eubacteria encodes two differently sized proteins (ca. 79 and 93 kDa) via dual translational initiation sites within the clpB transcript (5, 23).ClpB is essential for resistance to high-temperature stress. The cytosolic ClpB in Saccharomyces cerevisiae and plants confers acquired thermotolerance (9,18,19), which is commonly defined as the resistance developed by an organism to withstand an otherwise lethal temperature treatment by being preexposed to a nonlethal high temperature. Similarly, the heat shock-inducible ClpBI protein from the cyanobacterium Synechococcus sp. strain PCC 7942 (Synechococcus) is also crucial for thermotolerance (5), a role that can be complemented by Escherichia coli ClpB (6). In the case of ClpBI, both the fulllength and truncated forms of the protein contribute to the thermotolerance acquired by Synechococcus (3).Mechanistically, ClpB functions to dissolve inactive protein aggregates that accumulate at high temperatures (16). In both bacteria and eukaryotes, ClpB cooperates with the DnaKDnaJ-GrpE proteins in a bichaperone network to prevent and revert protein aggregates during heat shock (7,13,14). ClpB apparently dissolves large, stable heat-inactivated proteins by directly binding to aggregates and exposing hydrophobic surfaces within the polypeptides by ATP-induced structural changes in the ClpB protein (4, 8).All ClpB proteins studied to date are strongly induced by high temperatures, and most are vital for heat tolerance. Under nonstressed conditions, however, ClpB i...

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Acquired Thermotolerance and Expression of the HSP100/ClpB Genes of Lima Bean

Cited by 79 publications

References 30 publications

Characterization of a Small Heat Shock Protein, Mx Hsp16.6, of Myxococcus xanthus

Characterization of a Small Heat Shock Protein, Mx Hsp16.6, of Myxococcus xanthus

Introduction of the carrot HSP17.7 into potato (Solanum tuberosum L.) enhances cellular membrane stability and tuberization in vitro

Novel Form of ClpB/HSP100 Protein in the Cyanobacterium Synechococcus

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