Abstract
BackgroundThe 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.ResultsIn 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).ConclusionThe 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.
Highlights
The regulation of the chloroplast antioxidant capacity depends on nuclear gene expression
Isolation of Rap2.4a To identify cis-regulatory proteins involved in transcriptional regulation of 2-Cys peroxiredoxin-A gene (2CPA), a yeast-one-hybrid (Y1H) screen was performed with the 216 bp redox-active 2CPA promoter domain [11] and its flanking regions
Preys were provided by co-transformation of Y187 with a cDNA library derived from an Arabidopsis thaliana cell suspension culture [22]
Summary
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. Excess excitation energy supports formation of reactive oxygen species (ROS) [1] which can damage metabolites, enzymes and structures [2]. Antioxidant enzymes detoxify ROS, dissipate excess energy and regenerate the electron acceptors NADP+ and thioredoxin. As part of the acclimation to unfavourable growth conditions, expression of antioxidant enzymes increases under moderate stress conditions [3]. Under severe stress conditions gene expression decreases [4]. Accumulating ROS decrease the photosynthetic activity [1] and activate cytosolic defence mechanisms [1,7,8]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
