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Redox-mediated Mechanisms Regulate DNA Binding Activity of the G-group of Basic Region Leucine Zipper (bZIP) Transcription Factors in Arabidopsis
Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
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2012 (English)In: Journal of Biological Chemistry, ISSN 0021-9258, E-ISSN 1083-351X, Vol. 287, no 33, 27510-27525 p.Article in journal (Refereed) Published
Abstract [en]

Plant genes that contain the G-box in their promoters are responsive to a variety of environmental stimuli. Bioinformatics analysis of transcriptome data revealed that the G-box element is significantly enriched in promoters of high light-responsive genes. From nuclear extracts of high light-treated Arabidopsis plants, we identified the AtbZIP16 transcription factor as a component binding to the G-box-containing promoter fragment of light-harvesting chlorophyll a/b-binding protein2.4 (LHCB2.4). AtbZIP16 belongs to the G-group of Arabidopsis basic region leucine zipper (bZIP) type transcription factors. Although AtbZIP16 and its close homologues AtbZIP68 and AtGBF1 bind the G-box, they do not bind the mutated half-sites of the G-box palindrome. In addition, AtbZIP16 interacts with AtbZIP68 and AtGBF1 in the yeast two-hybrid system. A conserved Cys residue was shown to be necessary for redox regulation and enhancement of DNA binding activity in all three proteins. Furthermore, transgenic Arabidopsis lines overexpressing the wild type version of bZIP16 and T-DNA insertion mutants for bZIP68 and GBF1 demonstrated impaired regulation of LHCB2.4 expression. Finally, overexpression lines for the mutated Cys variant of bZIP16 provided support for the biological significance of Cys330 in redox regulation of gene expression. Thus, our results suggest that environmentally induced changes in the redox state regulate the activity of members of the G-group of bZIP transcription factors.

Place, publisher, year, edition, pages
Rockville: The American Society for Biochemistry and Molecular Biology , 2012. Vol. 287, no 33, 27510-27525 p.
National Category
Biochemistry and Molecular Biology
Identifiers
URN: urn:nbn:se:umu:diva-61574DOI: 10.1074/jbc.M112.361394ISI: 000307840700027OAI: oai:DiVA.org:umu-61574DiVA: diva2:572454
Available from: 2012-11-27 Created: 2012-11-20 Last updated: 2017-12-07Bibliographically approved
In thesis
1. Coordination of two different genomes in response to light and stress
Open this publication in new window or tab >>Coordination of two different genomes in response to light and stress
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Alternative title[sv]
Hur två olika genom samarbetar under ljus och stress respons
Abstract [en]

About 1.5 billion years ago, a photosynthetic bacteria was engulfed by a eukaryotic cell which initiated a symbiotic relationship and the evolution of the chloroplast as we know it today. The chloroplast has retained its own genome encoding for a number of proteins required for the function of the chloroplast. However, during the evolution most genes were transferred to the nucleus and the chloroplast is thus dependent on the nucleus to provide the majority of proteins necessary for its function. The distribution of genes encoding plastid proteins between two different cellular compartments requires a tight communication in order to coordinate gene expression during different growth conditions. The focus of my PhD studies has been to elucidate signalling pathways between the chloroplast and nucleus that enables the coordination of these two genomes in response to light and stress. The results in this thesis demonstrate that chloroplast retrograde signals triggered by changes in tetrapyrrole levels are important both in response to day-night cycles and during the response to stress. We identified a cytosolic regulatory complex and a novel mechanism that could explain how the tetrapyrrole-mediated signal can be transduced from the plastid to the nucleus and regulate nuclear gene expression in response to changes in the environment. My work further demonstrates that the tetrapyrrole-triggered plastid signalling pathway integrates with the circadian clock in order to fine-tune nuclear gene expression during photoperiodic conditions. These findings provide novel insight into how clock components and plastid signals converge in order to obtain the proper output. I have also examined the regulation of nuclear gene expression in response to redox and early-light signals by identifying transcription factors responding to these signals. My work demonstrates a novel mechanism by which redox-regulation of specific transcription factors directly links cellular redox status to gene regulation. The identified transcription factors were further shown to regulate nuclear genes encoding plastid proteins and they are of particular importance for anterograde control during the early light response and establishment of photomorphogenic growth.

Place, publisher, year, edition, pages
Umeå: Umeå University, 2016. 100 p.
Keyword
Arabidopsis thaliana, chloroplast, cellular communication, tetrapyrrole, circadian clock, oxidative stress, light signalling, gene regulation
National Category
Biochemistry and Molecular Biology
Research subject
Molecular Biology
Identifiers
urn:nbn:se:umu:diva-125373 (URN)978-91-7601-550-6 (ISBN)
Public defence
2016-10-06, KB3A9, KBC-huset, Umeå, 10:00 (English)
Opponent
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Available from: 2016-09-15 Created: 2016-09-09 Last updated: 2017-03-17Bibliographically approved

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Shaikhali, JehadNorén, LouiseBarajas-Lopez, Juan de DiosSauer, Uwe H.Strand, Åsa
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Department of Plant PhysiologyUmeå Plant Science Centre (UPSC)Department of Chemistry
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