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AtTRP1 encodes a novel TPR protein that interacts with the ethylene receptor ERS1 and modulates development in Arabidopsis.

Lin Z, Ho CW, Grierson D - J. Exp. Bot. (2009)

Bottom Line: This association was confirmed by in vivo co-immunoprecipitation.Plants overexpressing AtTRP1 also showed a reduced response to exogenous IAA and altered expression of a subset of auxin early responsive genes.A model for AtTRP1 action is proposed.

View Article: PubMed Central - PubMed

Affiliation: Plant and Crop Sciences Division, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, UK.

ABSTRACT
Arabidopsis AtTRP1 is an orthologue of SlTPR1, a tomato tetratricopeptide repeat protein that interacts with the tomato ethylene receptors LeETR1 and NR in yeast 2-hybrid assays and in vitro, and modulates plant development. AtTRP1 is encoded by a single copy gene in the Arabidopsis genome, and is related to TCC1, a human protein that competes with Raf-1 for Ras binding, and distantly related to the immunophilin-like FK-binding proteins TWD1 and PAS1. The former is involved in auxin transport and the latter is translocated to the nucleus in response to auxin. AtTRP1 interacted preferentially with the Arabidopsis ethylene receptor ERS1 in yeast two-hybrid assays. This association was confirmed by in vivo co-immunoprecipitation. AtTRP1 promoter-GUS was highly expressed in vascular tissue, mature anthers, the abscission zone, and was induced by ACC. Overexpression of AtTRP1 in wild-type Arabidopsis resulted in dwarf plants with reduced fertility, altered leaf/silique morphology, and enhanced expression of the ethylene responsive gene AtChitB. Exogenous GA did not reverse the dwarf habit. Etiolated transgenic seedlings overexpressing AtTRP1 displayed enhanced sensitivity to low ACC and this was correlated with the transgene expression. Seedlings overexpressing AtTRP1 at high levels exhibited shortened and swollen hypocotyls, inhibited root growth, and an altered apical hook. Plants overexpressing AtTRP1 also showed a reduced response to exogenous IAA and altered expression of a subset of auxin early responsive genes. These results indicated that overexpression of AtTRP1 affects cross-talk between ethylene and auxin signalling and enhances some ethylene responses and alters some auxin responses. A model for AtTRP1 action is proposed.

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A model of AtTRP1 action. AtTRP1 functions as a positive regulator to modulate ethylene signalling possibly through its interaction with one or more ethylene receptors the ethylene receptors. The exact mechanisms of AtTRP1 function remain to be elucidated, but it may compete with CTR1 for receptor binding, leading to increased ethylene responses; or it may function as an adaptor to bring a receptor for degradation. Increased ethylene responses caused by constitutive overexpression of AtTRP1 led to cross-talk with auxin via SAUR-AC1 and IAA5 at least, and possible also with GA signalling. AtTRP1 may directly interact with auxin signalling components as well.
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fig11: A model of AtTRP1 action. AtTRP1 functions as a positive regulator to modulate ethylene signalling possibly through its interaction with one or more ethylene receptors the ethylene receptors. The exact mechanisms of AtTRP1 function remain to be elucidated, but it may compete with CTR1 for receptor binding, leading to increased ethylene responses; or it may function as an adaptor to bring a receptor for degradation. Increased ethylene responses caused by constitutive overexpression of AtTRP1 led to cross-talk with auxin via SAUR-AC1 and IAA5 at least, and possible also with GA signalling. AtTRP1 may directly interact with auxin signalling components as well.

Mentions: AtTRP1, an orthologue of the tomato TPR protein SlTPR1 that interacts with the tomato ethylene receptors NR and LeETR1 in yeast two-hybrid and in vitro pull-down assays and that modulates plant development, has been characterized (Lin et al., 2008b). The designation of AtTRP1 is proposed for the Arabidopsis gene because AtTPR1 is already in use. AtTRP1, like SlTPR1, is closely related to TTC1, a human TPR protein (Fig. 2A) which links G-proteins and Ras signalling in mammalian cells and competes with Raf-1 for Ras-binding (Marty et al., 2003). AtTRP1 shares overall 72% similarity to SlTPR1 and 52% to TTC1 at the protein sequence level. This sequence similarity between AtTRP1/SlTPR1 and TTC1 suggests that they may possess similar functions. Although no Ras-like proteins are found in plants, the interaction of AtTRP1 with the ethylene receptor may compete for receptor binding with CTR1, a Raf-like protein, and modulate ethylene signalling (Fig. 11).


AtTRP1 encodes a novel TPR protein that interacts with the ethylene receptor ERS1 and modulates development in Arabidopsis.

Lin Z, Ho CW, Grierson D - J. Exp. Bot. (2009)

A model of AtTRP1 action. AtTRP1 functions as a positive regulator to modulate ethylene signalling possibly through its interaction with one or more ethylene receptors the ethylene receptors. The exact mechanisms of AtTRP1 function remain to be elucidated, but it may compete with CTR1 for receptor binding, leading to increased ethylene responses; or it may function as an adaptor to bring a receptor for degradation. Increased ethylene responses caused by constitutive overexpression of AtTRP1 led to cross-talk with auxin via SAUR-AC1 and IAA5 at least, and possible also with GA signalling. AtTRP1 may directly interact with auxin signalling components as well.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC2736885&req=5

fig11: A model of AtTRP1 action. AtTRP1 functions as a positive regulator to modulate ethylene signalling possibly through its interaction with one or more ethylene receptors the ethylene receptors. The exact mechanisms of AtTRP1 function remain to be elucidated, but it may compete with CTR1 for receptor binding, leading to increased ethylene responses; or it may function as an adaptor to bring a receptor for degradation. Increased ethylene responses caused by constitutive overexpression of AtTRP1 led to cross-talk with auxin via SAUR-AC1 and IAA5 at least, and possible also with GA signalling. AtTRP1 may directly interact with auxin signalling components as well.
Mentions: AtTRP1, an orthologue of the tomato TPR protein SlTPR1 that interacts with the tomato ethylene receptors NR and LeETR1 in yeast two-hybrid and in vitro pull-down assays and that modulates plant development, has been characterized (Lin et al., 2008b). The designation of AtTRP1 is proposed for the Arabidopsis gene because AtTPR1 is already in use. AtTRP1, like SlTPR1, is closely related to TTC1, a human TPR protein (Fig. 2A) which links G-proteins and Ras signalling in mammalian cells and competes with Raf-1 for Ras-binding (Marty et al., 2003). AtTRP1 shares overall 72% similarity to SlTPR1 and 52% to TTC1 at the protein sequence level. This sequence similarity between AtTRP1/SlTPR1 and TTC1 suggests that they may possess similar functions. Although no Ras-like proteins are found in plants, the interaction of AtTRP1 with the ethylene receptor may compete for receptor binding with CTR1, a Raf-like protein, and modulate ethylene signalling (Fig. 11).

Bottom Line: This association was confirmed by in vivo co-immunoprecipitation.Plants overexpressing AtTRP1 also showed a reduced response to exogenous IAA and altered expression of a subset of auxin early responsive genes.A model for AtTRP1 action is proposed.

View Article: PubMed Central - PubMed

Affiliation: Plant and Crop Sciences Division, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, UK.

ABSTRACT
Arabidopsis AtTRP1 is an orthologue of SlTPR1, a tomato tetratricopeptide repeat protein that interacts with the tomato ethylene receptors LeETR1 and NR in yeast 2-hybrid assays and in vitro, and modulates plant development. AtTRP1 is encoded by a single copy gene in the Arabidopsis genome, and is related to TCC1, a human protein that competes with Raf-1 for Ras binding, and distantly related to the immunophilin-like FK-binding proteins TWD1 and PAS1. The former is involved in auxin transport and the latter is translocated to the nucleus in response to auxin. AtTRP1 interacted preferentially with the Arabidopsis ethylene receptor ERS1 in yeast two-hybrid assays. This association was confirmed by in vivo co-immunoprecipitation. AtTRP1 promoter-GUS was highly expressed in vascular tissue, mature anthers, the abscission zone, and was induced by ACC. Overexpression of AtTRP1 in wild-type Arabidopsis resulted in dwarf plants with reduced fertility, altered leaf/silique morphology, and enhanced expression of the ethylene responsive gene AtChitB. Exogenous GA did not reverse the dwarf habit. Etiolated transgenic seedlings overexpressing AtTRP1 displayed enhanced sensitivity to low ACC and this was correlated with the transgene expression. Seedlings overexpressing AtTRP1 at high levels exhibited shortened and swollen hypocotyls, inhibited root growth, and an altered apical hook. Plants overexpressing AtTRP1 also showed a reduced response to exogenous IAA and altered expression of a subset of auxin early responsive genes. These results indicated that overexpression of AtTRP1 affects cross-talk between ethylene and auxin signalling and enhances some ethylene responses and alters some auxin responses. A model for AtTRP1 action is proposed.

Show MeSH
Related in: MedlinePlus