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The redox-sensitive transcription factor Rap2.4a controls nuclear expression of 2-Cys peroxiredoxin A and other chloroplast antioxidant enzymes.

Shaikhali J, Heiber I, Seidel T, Ströher E, Hiltscher H, Birkmann S, Dietz KJ, Baier M - BMC Plant Biol. (2008)

Bottom Line: Rap2.4a activity is regulated by dithiol/disulfide transition of regulatory cysteinyl residues and subsequent changes in the quaternary structure.The mid-point redox potential of Rap2.4a activation is -269 mV (pH 7.0).The redox sensitivity of Rap2.4a establishes an efficient switch mechanism for redox control of nuclear gene activity of chloroplast antioxidants, in which Rap2.4 is a redox-sensor and a transducer of redox information.

View Article: PubMed Central - HTML - PubMed

Affiliation: Plant Biochemistry and Physiology, Bielefeld University, 33501 Bielefeld, Germany. jehadgermany@gmx.de

ABSTRACT

Background: The regulation of the chloroplast antioxidant capacity depends on nuclear gene expression. For the 2-Cys peroxiredoxin-A gene (2CPA) a cis-regulatory element was recently characterized, which responds to photosynthetic redox signals.

Results: In a yeast-one-hybrid screen for cis-regulatory binding proteins, the transcription factor Rap2.4a was isolated. Rap2.4a controls the transcript abundance of the prominent chloroplast antioxidant enzyme through binding to the CGCG core of a CE3-like element. Rap2.4a activity is regulated by dithiol/disulfide transition of regulatory cysteinyl residues and subsequent changes in the quaternary structure. The mid-point redox potential of Rap2.4a activation is -269 mV (pH 7.0).

Conclusion: The redox sensitivity of Rap2.4a establishes an efficient switch mechanism for redox control of nuclear gene activity of chloroplast antioxidants, in which Rap2.4 is a redox-sensor and a transducer of redox information.

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Localization of Rap2.4a-YFP (A) and ABI5-YFP (B) in Arabidopsis mesophyll protoplasts. green: YFP fluorescence; red: chlorophyll fluorescence. (C) Relative YFP activity in the nucleus as calculated from integration of the signal strength in 2D images (n = 8 - 10).
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Figure 3: Localization of Rap2.4a-YFP (A) and ABI5-YFP (B) in Arabidopsis mesophyll protoplasts. green: YFP fluorescence; red: chlorophyll fluorescence. (C) Relative YFP activity in the nucleus as calculated from integration of the signal strength in 2D images (n = 8 - 10).

Mentions: Since Rap2.4a lacks a strong nuclear localization signal and chloroplast targeting has been suggested for the Ib-ERF Rap2.4c (At2g22200) [28], the distribution of Rap2.4a protein was analysed in Arabidopsis protoplasts expressing Rap2.4a-YFP fusion proteins by confocal laser scanning microscopy (CLSM) (Fig. 3). After 12 h incubation, the majority of the protein (92 ± 7 %) was observed in the nucleus like for the YFP-fusion protein of the basic helix-loop-helix transcription factor ABI5 (97 ± 2 %), while only 53 ± 5 % of free YFP was detected in the nucleus (Fig. 3).


The redox-sensitive transcription factor Rap2.4a controls nuclear expression of 2-Cys peroxiredoxin A and other chloroplast antioxidant enzymes.

Shaikhali J, Heiber I, Seidel T, Ströher E, Hiltscher H, Birkmann S, Dietz KJ, Baier M - BMC Plant Biol. (2008)

Localization of Rap2.4a-YFP (A) and ABI5-YFP (B) in Arabidopsis mesophyll protoplasts. green: YFP fluorescence; red: chlorophyll fluorescence. (C) Relative YFP activity in the nucleus as calculated from integration of the signal strength in 2D images (n = 8 - 10).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2386467&req=5

Figure 3: Localization of Rap2.4a-YFP (A) and ABI5-YFP (B) in Arabidopsis mesophyll protoplasts. green: YFP fluorescence; red: chlorophyll fluorescence. (C) Relative YFP activity in the nucleus as calculated from integration of the signal strength in 2D images (n = 8 - 10).
Mentions: Since Rap2.4a lacks a strong nuclear localization signal and chloroplast targeting has been suggested for the Ib-ERF Rap2.4c (At2g22200) [28], the distribution of Rap2.4a protein was analysed in Arabidopsis protoplasts expressing Rap2.4a-YFP fusion proteins by confocal laser scanning microscopy (CLSM) (Fig. 3). After 12 h incubation, the majority of the protein (92 ± 7 %) was observed in the nucleus like for the YFP-fusion protein of the basic helix-loop-helix transcription factor ABI5 (97 ± 2 %), while only 53 ± 5 % of free YFP was detected in the nucleus (Fig. 3).

Bottom Line: Rap2.4a activity is regulated by dithiol/disulfide transition of regulatory cysteinyl residues and subsequent changes in the quaternary structure.The mid-point redox potential of Rap2.4a activation is -269 mV (pH 7.0).The redox sensitivity of Rap2.4a establishes an efficient switch mechanism for redox control of nuclear gene activity of chloroplast antioxidants, in which Rap2.4 is a redox-sensor and a transducer of redox information.

View Article: PubMed Central - HTML - PubMed

Affiliation: Plant Biochemistry and Physiology, Bielefeld University, 33501 Bielefeld, Germany. jehadgermany@gmx.de

ABSTRACT

Background: The regulation of the chloroplast antioxidant capacity depends on nuclear gene expression. For the 2-Cys peroxiredoxin-A gene (2CPA) a cis-regulatory element was recently characterized, which responds to photosynthetic redox signals.

Results: In a yeast-one-hybrid screen for cis-regulatory binding proteins, the transcription factor Rap2.4a was isolated. Rap2.4a controls the transcript abundance of the prominent chloroplast antioxidant enzyme through binding to the CGCG core of a CE3-like element. Rap2.4a activity is regulated by dithiol/disulfide transition of regulatory cysteinyl residues and subsequent changes in the quaternary structure. The mid-point redox potential of Rap2.4a activation is -269 mV (pH 7.0).

Conclusion: The redox sensitivity of Rap2.4a establishes an efficient switch mechanism for redox control of nuclear gene activity of chloroplast antioxidants, in which Rap2.4 is a redox-sensor and a transducer of redox information.

Show MeSH