| 1. |
- Ng, Sophia, et al.
(author)
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A Membrane-Bound NAC Transcription Factor, ANAC017, Mediates Mitochondrial Retrograde Signaling in Arabidopsis
- 2013
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In: The Plant Cell. - : Oxford University Press (OUP). - 1040-4651 .- 1532-298X. ; 25:9, s. 3450-3471
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Journal article (peer-reviewed)abstract
- Plants require daily coordinated regulation of energy metabolism for optimal growth and survival and therefore need to integrate cellular responses with both mitochondrial and plastid retrograde signaling. Using a forward genetic screen to characterize regulators of alternative oxidase1a (rao) mutants, we identified RAO2/Arabidopsis NAC domain-containing protein17 (ANAC017) as a direct positive regulator of AOX1a. RAO2/ANAC017 is targeted to connections and junctions in the endoplasmic reticulum (ER) and F-actin via a C-terminal transmembrane (TM) domain. A consensus rhomboid protease cleavage site is present in ANAC017 just prior to the predicted TM domain. Furthermore, addition of the rhomboid protease inhibitor N-p-Tosyl-L-Phe chloromethyl abolishes the induction of AOX1a upon antimycin A treatment. Simultaneous fluorescent tagging of ANAC017 with N-terminal red fluorescent protein (RFP) and C-terminal green fluorescent protein (GFP) revealed that the N-terminal RFP domain migrated into the nucleus, while the C-terminal GFP tag remained in the ER. Genome-wide analysis of the transcriptional network regulated by RAO2/ANAC017 under stress treatment revealed that RAO2/ANAC017 function was necessary for > 85% of the changes observed as a primary response to cytosolic hydrogen peroxide (H2O2), but only; 33% of transcriptional changes observed in response to antimycin A treatment. Plants with mutated rao2/anac017 were more stress sensitive, whereas a gain-of-function mutation resulted in plants that had lower cellular levels of H2O2 under untreated conditions.
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| 2. |
- Ng, Sophia, et al.
(author)
-
Cyclin-dependent Kinase E1 (CDKE1) Provides a Cellular Switch in Plants between Growth and Stress Responses
- 2013
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In: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 288:5, s. 3449-3459
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Journal article (peer-reviewed)abstract
- Plants must deal effectively with unfavorable growth conditions that necessitate a coordinated response to integrate cellular signals with mitochondrial retrograde signals. A genetic screen was carried out to identify regulators of alternative oxidase (rao mutants), using AOX1a expression as a model system to study retrograde signaling in plants. Two independent rao1 mutant alleles identified CDKE1 as a central nuclear component integrating mitochondrial retrograde signals with energy signals under stress. CDKE1 is also necessary for responses to general cellular stresses, such as H2O2 and cold that act, at least in part, via anterograde pathways, and integrates signals from central energy/stress sensing kinase signal transduction pathways within the nucleus. Together, these results place CDKE1 as a central kinase integrating diverse cellular signals and shed light on a mechanism by which plants can effectively switch between growth and stress responses.
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