Three tomato genes code for heat stress transcription factors with a region of remarkable homology to the DNA-binding domain of the yeast HSF.

Scharf, Klaus‐Dieter; Rose, Stephanie; Zott, W.; Schöffl, Fritz; Nover, Lutz; Schöff, F.

doi:10.1002/j.1460-2075.1990.tb07900.x

Cited by 296 publications

(205 citation statements)

References 39 publications

(51 reference statements)

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“…Based on our results with the CS plants, we must conclude that the deficiency of HsfA1 expression cannot be complemented by any of the other closely related tomato Hsfs. Although our knowledge is still very limited, the functional analysis of the four tomato Hsfs cloned so far supports the concept of a marked diversification (Scharf et al 1990(Scharf et al , 1998Treuter et al 1993;Boscheinen et al 1997;Lyck et al 1997;Bharti et al 2000;Döring et al 2000;Heerklotz et al 2001). Evidently, each of these Hsfs has its own role in a complex network determined by the pattern of expression, intracellular localization, oligomerization behavior, activator function, and interaction of Hsfs with other proteins (for review, see Nover et al 2001).…”

Section: Functional Diversification Of Tomato Hsfsmentioning

confidence: 72%

“…Moneymaker), the Agrobacterium tumefaciens strain GV3101(pMP90) was used as described (Koncz and Schell 1986). The binary vector pGPTV-KAN (Becker et al 1992) was modified by removing the ␤-glucuronidase (uid A) gene and insertion of the HindIII fragment containing the HsfA1 cDNA expression cassette from the corresponding pRT vector (Scharf et al 1990). In the construct used for transformation, the expression cassette of HsfA1 with the cauliflower mosaic virus (CaMV) 35S promoter points towards the right T-DNA border (RB) and therefore opposite to the direction of the NPTII selection marker gene, whose expression is under the control of the NOS promoter (Fig.…”

Section: Generation and Selection Of Transgenic Plantsmentioning

confidence: 99%

“…The significance of these extended oligomerization domains for the oligomerization behavior and function of Hsfs is not yet clear. Another plant-specific feature with probably important consequences for details of the stress response is the fact that many Hsfs are hs-inducible proteins themselves (Scharf et al 1990(Scharf et al , 1998Nover et al 2001); for example, in tomato HsfA1 is constitutively expressed, whereas Hsfs A2 and B1 are hs-inducible proteins.…”

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In the complex family of heat stress transcription factors, HsfA1 has a unique role as master regulator of thermotolerance in tomato

Mishra¹,

Tripp²,

Winkelhaus³

et al. 2002

Genes Dev.

509

481

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We generated transgenic tomato plants with altered expression of heat stress transcription factor HsfA1. Plants with 10-fold overexpression of HsfA1 (OE plants) were characterized by a single HsfA1 transgene cassette, whereas plants harboring a tandem inverted repeat of the cassette showed cosuppression (CS plants) by posttranscriptional silencing of the HsfA1 gene connected with formation of small interfering RNAs. Under normal growth conditions, major developmental parameters were similar for wild-type (WT), OE, and CS plants. However, CS plants and fruits were extremely sensitive to elevated temperatures, because heat stress-induced synthesis of chaperones and Hsfs was strongly reduced or lacking. Despite the complexity of the plant Hsf family with at least 17 members in tomato, HsfA1 has a unique function as master regulator for induced thermotolerance. Using transient reporter assays with mesophyll protoplasts from WT tomato, we demonstrated that plasmid-encoded HsfA1 and HsfA2 were well expressed. However, in CS protoplasts the cosuppression phenomenon was faithfully reproduced. Only transformation with HsfA2 expression plasmid led to normal expression of the transcription factor and reporter gene activation, whereas even high amounts of HsfA1 expression plasmids were silenced. Thermotolerance in CS protoplasts was restored by plasmid-borne HsfA2, resulting in expression of chaperones, thermoprotection of firefly luciferase, and assembly of heat stress granules. (Pelham 1982;Pelham and Bienz 1982;Nover 1987). Similar to other transcription factors, Hsfs have a modular structure with an N-terminal DNA-binding domain characterized by a central helix-turn-helix motif, an adjacent oligomerization domain with a bipartite heptad pattern of hydrophobic amino acid residues (HR-A/B region), and sequence motifs essential for nuclear import and export (NLS, NES;Wu 1995;Morimoto 1998;Heerklotz et al. 2001;Nover et al. 2001). In many cases, the C-terminal activation domains are characterized by short peptide motifs (AHA motifs) shown to be crucial for the activator function (Döring et al. 2000).Sequencing of the Arabidopsis genome revealed a unique complexity of the Hsf family with 21 members, in contrast to yeast and Drosophila with one Hsf and vertebrates with four Hsfs (Wu 1995;Nover et al. 2001). From analyses of expressed sequence tag (EST) libraries, it is evident that the size of the Hsf family is comparable also in other plants, with 17 Hsfs thus far identified from tomato ESTs . By structural characteristics and phylogenetic comparison, plant Hsfs were assigned to three classes. In Arabidopsis, there are 15

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Section: Functional Diversification Of Tomato Hsfsmentioning

confidence: 72%

Section: Generation and Selection Of Transgenic Plantsmentioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

In the complex family of heat stress transcription factors, HsfA1 has a unique role as master regulator of thermotolerance in tomato

Mishra¹,

Tripp²,

Winkelhaus³

et al. 2002

Genes Dev.

509

481

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“…lactis (Jakobsen and Pelham, 1991), Drosophila (Clos et al, 1990), human (Rabindran et al, 1991), mouse (Sarge et al, 1991) and tomato (Scharf et al, 1990). In yeast, HSF is a single copy essential gene whilst in man and mouse two alleles have been identified.…”

Section: Introductionmentioning

confidence: 99%

Identification of the C-terminal activator domain in yeast heat shock factor: independent control of transient and sustained transcriptional activity.

et al. 1993

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In yeast, heat shock factor (HSF) is a trimer that binds DNA constitutively but only supports high levels of transcription upon heat shock. The C-terminal regions of HSF from Saccharomyces cerevisiae and Kluyveromyces lactis are unconserved yet both contain strong transactivators which are correctly regulated when substituted for each other. We have performed high resolution mapping of these activator domains which shows that in K.lacts HSF (KIHSF) activity can be located to a confined short domain, while in S.cerevisiae HSF (ScHSF) two separate regions are required for full activity. Alignment of the activator domains reveals similarity, as both overlap potential leucine zipper motifs (zipper C) with a distribution of hydrophobic residues sinilar to two highly conserved N-terminal domains which mediate HSF trimerization (zippers A and B). In higher eukaryotes a C-terminal leucine zipper is required to maintain HSF in a monomeric and non DNA-binding state under normal conditions and we therefore address the regulatory roles of the three leucine zipper motifs in KIHSF. Whilst the longest and most N-terminal of the trimer region zippers, A, is dispensable for regulation, mutation of a single leucine in zipper B makes HSF constitutively active. In contrast to the situation in higher eukaryotes disruption of zipper C has no observable regulatory effect and therefore, although an intramolecular contact between zippers B and C cannot be ruled out, such contact is not required for restraining the C-terminal activator domain. We furthermore fimd that deletions which abolish activator potential of the C-terminus render the host strain temperature sensitive.However, deletion of a double proline-glycine motif in the activator, whilst leaving HSF unable to respond to heat shock, does not cause temperature sensitivity. This result demonstrates that independent mechanisms control the transient and sustained activities of HSF.

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“…Many hsps were identified in yeast cells, and some of the respective genes have been cloned. Some of these genes are highly homologous to each other and form subfam- (14,21,30,52,60,61,70,82). The HSF acts as a multimer (50,53,81) and in most organisms binds the HSE only upon heat shock (36,67,68).…”

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confidence: 99%

The yeast and mammalian Ras pathways control transcription of heat shock genes independently of heat shock transcription factor.

Engelberg¹,

Zandi²,

Parker³

et al. 1994

Mol. Cell. Biol.

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Yeast strains in which the Ras-cyclic AMP (cAMP) pathway is constitutively active are sensitive to heat shock, whereas mutants in which the activity of this pathway is low are hyperresistant to heat shock. To determine the molecular basis for these differences, we examined the transcriptional induction of heat shock genes in various yeast strains. Activation of heat shock genes was attenuated in the strains in which the Ras-cAMP pathway is constitutively active. In contrast, in a strain deficient in cAMP production, several heat shock genes were induced by removal of cAMP from the medium. These results indicate that the Ras-cAMP pathway affects the induction of heat shock genes. In all of the mutants, heat shock transcription factor expression and activity were identical to those in wild-type cells. The response to heat shock in Ha-rastransformed rat fibroblasts was also studied. While no induction of Hsp68 was observed in Ha-ras-transformed cells, proper regulation of heat shock transcription factor was found. Therefore, in mammals, as in Saccharomyces cerevisiae, the Ras pathway controls the transcription of heat shock genes via a mechanism not involving the heat shock transcription factor.The ras proto-oncogenes are highly conserved from yeasts to humans (reviewed in reference 12). These genes encode small membrane-associated GTP binding proteins that transduce signals generated at the cell surface to intracellular effectors (3,7,24,59). The mammalian Ha-Ras protein seems to interact with the serine or threonine kinase [77][78][79]85) and somehow leads to its activation. This results in activation of a protein kinase cascade (18,73,83) that induces gene expression through phosphorylation of transcription factors (reviewed in reference 25). One transcription factor affected by Ha-Ras is c-Jun (6), and another is NF-KB (17). In addition to positive modulation of the transcription factors' activity, HaRas may also negatively regulate certain transcription factors.In the yeast Saccharomyces cerevisiae, It was shown that expression of heat shock proteins (hsps) under nonshock conditions confers hyperresistance to heat shock (27,42,56). Therefore, it seems reasonable that resistance and sensitivity to heat shock are mediated at the level of hsp gene transcription. Indeed, it was shown that cyri cells express three proteins with a molecular mass of 72 kDa (65). These proteins, which were probably hsps, were not induced in the bcyl strain (65). Other studies showed that one of the heat shock genes, SSA3, was activated in the cyril strain in the absence of heat shock (9, 80). Also, the UBI4 gene, coding for polyubiquitin, was found to be regulated both by heat shock and cAMP (72). It is still not known, however, whether the Ras-cAMP pathway is a general regulator of hsp gene expression. It is also not known whether mammalian Ha-Ras activation also affects hsp gene expression. Furthermore, both in yeasts and in mammals, the relationship between the Ras pathway and the heat shock transcription factor (HSF [described bel...

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Three tomato genes code for heat stress transcription factors with a region of remarkable homology to the DNA-binding domain of the yeast HSF.

Abstract: Heat stress (hs) treatment of cell cultures of Lycopersicon peruvianum (Lp, tomato)

Cited by 296 publications

References 39 publications

In the complex family of heat stress transcription factors, HsfA1 has a unique role as master regulator of thermotolerance in tomato

In the complex family of heat stress transcription factors, HsfA1 has a unique role as master regulator of thermotolerance in tomato

Identification of the C-terminal activator domain in yeast heat shock factor: independent control of transient and sustained transcriptional activity.

The yeast and mammalian Ras pathways control transcription of heat shock genes independently of heat shock transcription factor.

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