The Transcription Factor ABI4 Is a Regulator of Mitochondrial Retrograde Expression of ALTERNATIVE OXIDASE1a

• Published in: Plant physiology (Bethesda) 2009-07, Vol.150 (3), p.1286-1296
• Main Authors: Giraud, Estelle, Van Aken, Olivier, Ho, Lois H. M., Whelan, James
• Format: Article
• Language: English
• Subjects: Abscisic Acid - metabolism; Abscisic Acid - pharmacology; Arabidopsis - genetics; Arabidopsis - metabolism; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Arabidopsis Proteins - physiology; Binding Sites; Bioenergetics and Photosynthesis; Biological and medical sciences; Chloroplasts; Fundamental and applied biological sciences. Psychology; Gene expression; Gene expression regulation; Gene Expression Regulation, Plant - drug effects; Genes; Mitochondria - metabolism; Mitochondrial Proteins; Oxidases; Oxidoreductases - genetics; Oxidoreductases - metabolism; Plant cells; Plant Growth Regulators - metabolism; Plant Growth Regulators - pharmacology; Plant physiology and development; Plant Proteins; Plants; Promoter regions; Promoter Regions, Genetic; Protein Interaction Mapping; RNA, Messenger - metabolism; Transcription factors; Transcription Factors - genetics; Transcription Factors - metabolism; Transcription Factors - physiology; Yeasts
• ISSN: 0032-0889; 1532-2548; 1532-2548
• DOI: 10.1104/pp.109.139782

Plant cells integrate signals from external sources and from organelles to regulate gene expression, referred to as anterograde and retrograde signaling, respectively. Functional characterization of the promoter of ALTERNATIVE OXIDASEla (AOXla) from Arabidopsis (Arabidopsis thaliana), a marker for mitochondrial retrograde response, was carried out by testing the ability of the AOXla promoter to drive expression of the reporter gene GUS. This approach identified a strong repressor element, designated the B element, that was necessary for an increased promoter activity in response to the mitochondrial complex I inhibitor rotenone. This element overlaps with a previously identified potential binding site for the transcription factor ABSCISIC ACID INSENSITIVE4 (ABI4). AOXla promoter activity was fully derepressed in abi4 mutants and was unresponsive to rotenone. Furthermore, deletion of the B element of the AOXla promoter resulted in increased GUS staining activity compared to the wildtype promoter in transgenic plants. Binding of the ABI4 transcription factor to this region of the AOXla promoter was demonstrated by electromobility shift and yeast one-hybrid assays. Analysis of transcript abundance for AOXla in abi4 mutant lines revealed significantly increased levels of AOXla mRNA that could not be further induced by rotenone, consistent with the role of ABI4 as a repressor that is derepressed in response to rotenone. These results show that ABI4 plays a central role in mediating mitochondrial retrograde signals to induce the expression of AOXla. Furthermore, they provide a molecular link between mitochondrial and chloroplast retrograde signaling, as ABI4 has been previously shown to act downstream of at least two chloroplast retrograde signaling pathways