title: AtWRKY40 and AtWRKY63 modulate the expression of stress-responsive nuclear genes encoding mitochondrial and chloroplast proteins.
abstract: The expression of a variety of nuclear genes encoding mitochondrial proteins is known to adapt to changes in environmental conditions and retrograde signaling. The presence of putative WRKY transcription factor binding sites (W-boxes) in the promoters of many of these genes prompted a screen of 72 annotated WRKY factors in the Arabidopsis (Arabidopsis thaliana) genome for regulators of transcripts encoding mitochondrial proteins. A large-scale yeast one-hybrid screen was used to identify WRKY factors that bind the promoters of marker genes (Alternative oxidase1a, NADH dehydrogenaseB2, and the AAA ATPase Ubiquinol-cytochrome c reductase synthesis1), and interactions were confirmed using electromobility shift assays. Transgenic overexpression and knockout lines for 12 binding WRKY factors were generated and tested for altered expression of the marker genes during normal and stress conditions. AtWRKY40 was found to be a repressor of antimycin A-induced mitochondrial retrograde expression and high-light-induced signaling, while AtWRKY63 was identified as an activator. Genome-wide expression analysis following high-light stress in transgenic lines with perturbed AtWRKY40 and AtWRKY63 function revealed that these factors are involved in regulating stress-responsive genes encoding mitochondrial and chloroplast proteins but have little effect on more constitutively expressed genes encoding organellar proteins. Furthermore, it appears that AtWRKY40 and AtWRKY63 are particularly involved in regulating the expression of genes responding commonly to both mitochondrial and chloroplast dysfunction but not of genes responding to either mitochondrial or chloroplast perturbation. In conclusion, this study establishes the role of WRKY transcription factors in the coordination of stress-responsive genes encoding mitochondrial and chloroplast proteins.
authors.affiliation: Australian Research Council Centre of Excellence in Plant Energy Biology, Crawley 6009, Western Australia, Australia.
authors.forename: Olivier
authors.initials: O
authors.lastname: Van Aken
authors.forename: Botao
authors.initials: B
authors.lastname: Zhang
authors.forename: Simon
authors.initials: S
authors.lastname: Law
authors.forename: Reena
authors.initials: R
authors.lastname: Narsai
authors.forename: James
authors.initials: J
authors.lastname: Whelan
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000502:physiology; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D060365:Chloroplast Proteins / Q000235:genetics / Q000378:metabolism; D002736:Chloroplasts / Q000235:genetics / Q000378:metabolism; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D055786:Gene Knockout Techniques; D018745:Genome, Plant / Q000235:genetics; D008928:Mitochondria / Q000235:genetics / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism; D016254:Mutagenesis, Insertional; D020411:Oligonucleotide Array Sequence Analysis; D030821:Plants, Genetically Modified; D011401:Promoter Regions, Genetic / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics; D018749:RNA, Plant / Q000235:genetics; D013312:Stress, Physiological; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D020798:Two-Hybrid System Techniques
chemical_list: D029681:Arabidopsis Proteins; D060365:Chloroplast Proteins; D024101:Mitochondrial Proteins; D012333:RNA, Messenger; D018749:RNA, Plant; D014157:Transcription Factors; C512070:WRKY40 protein, Arabidopsis; C585191:WRKY63 protein, Arabidopsis