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Hoffmann RD, Olsen LI, Ezike CV, Pedersen JT, Manstretta R, López-Marqués RL, Palmgren M. Roles of plasma membrane proton ATPases AHA2 and AHA7 in normal growth of roots and root hairs in Arabidopsis thaliana. Physiol Plant 2019; 166:848-861. [PMID: 30238999 PMCID: PMC7379730 DOI: 10.1111/ppl.12842] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Revised: 09/14/2018] [Accepted: 09/17/2018] [Indexed: 05/18/2023]
Abstract
Plasma membrane H+ -ATPase pumps build up the electrochemical H+ gradients that energize most other transport processes into and out of plant cells through channel proteins and secondary active carriers. In Arabidopsis thaliana, the AUTOINHIBITED PLASMA MEMBRANE H+ -ATPases AHA1, AHA2 and AHA7 are predominant in root epidermal cells. In contrast to other H+ -ATPases, we find that AHA7 is autoinhibited by a sequence present in the extracellular loop between transmembrane segments 7 and 8. Autoinhibition of pump activity was regulated by extracellular pH, suggesting negative feedback regulation of AHA7 during establishment of an H+ gradient. Due to genetic redundancy, it has proven difficult to test the role of AHA2 and AHA7, and mutant phenotypes have previously only been observed under nutrient stress conditions. Here, we investigated root and root hair growth under normal conditions in single and double mutants of AHA2 and AHA7. We find that AHA2 drives root cell expansion during growth but that, unexpectedly, restriction of root hair elongation is dependent on AHA2 and AHA7, with each having different roles in this process.
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Affiliation(s)
- Robert D. Hoffmann
- Department of Plant and Environmental SciencesUniversity of CopenhagenDK‐1871FrederiksbergDenmark
| | - Lene I. Olsen
- Department of Plant and Environmental SciencesUniversity of CopenhagenDK‐1871FrederiksbergDenmark
| | - Chukwuebuka V. Ezike
- Department of Plant and Environmental SciencesUniversity of CopenhagenDK‐1871FrederiksbergDenmark
| | - Jesper T. Pedersen
- Department of Plant and Environmental SciencesUniversity of CopenhagenDK‐1871FrederiksbergDenmark
| | - Raffaele Manstretta
- Department of Plant and Environmental SciencesUniversity of CopenhagenDK‐1871FrederiksbergDenmark
| | - Rosa L. López-Marqués
- Department of Plant and Environmental SciencesUniversity of CopenhagenDK‐1871FrederiksbergDenmark
| | - Michael Palmgren
- Department of Plant and Environmental SciencesUniversity of CopenhagenDK‐1871FrederiksbergDenmark
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Imkampe J, Halter T, Huang S, Schulze S, Mazzotta S, Schmidt N, Manstretta R, Postel S, Wierzba M, Yang Y, van Dongen WMAM, Stahl M, Zipfel C, Goshe MB, Clouse S, de Vries SC, Tax F, Wang X, Kemmerling B. The Arabidopsis Leucine-Rich Repeat Receptor Kinase BIR3 Negatively Regulates BAK1 Receptor Complex Formation and Stabilizes BAK1. Plant Cell 2017; 29:2285-2303. [PMID: 28842532 PMCID: PMC5635992 DOI: 10.1105/tpc.17.00376] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Revised: 07/28/2017] [Accepted: 08/25/2017] [Indexed: 05/18/2023]
Abstract
BAK1 is a coreceptor and positive regulator of multiple ligand binding leucine-rich repeat receptor kinases (LRR-RKs) and is involved in brassinosteroid (BR)-dependent growth and development, innate immunity, and cell death control. The BAK1-interacting LRR-RKs BIR2 and BIR3 were previously identified by proteomics analyses of in vivo BAK1 complexes. Here, we show that BAK1-related pathways such as innate immunity and cell death control are affected by BIR3 in Arabidopsis thaliana BIR3 also has a strong negative impact on BR signaling. BIR3 directly interacts with the BR receptor BRI1 and other ligand binding receptors and negatively regulates BR signaling by competitive inhibition of BRI1. BIR3 is released from BAK1 and BRI1 after ligand exposure and directly affects the formation of BAK1 complexes with BRI1 or FLAGELLIN SENSING2. Double mutants of bak1 and bir3 show spontaneous cell death and constitutive activation of defense responses. BAK1 and its closest homolog BKK1 interact with and are stabilized by BIR3, suggesting that bak1 bir3 double mutants mimic the spontaneous cell death phenotype observed in bak1 bkk1 mutants via destabilization of BIR3 target proteins. Our results provide evidence for a negative regulatory mechanism for BAK1 receptor complexes in which BIR3 interacts with BAK1 and inhibits ligand binding receptors to prevent BAK1 receptor complex formation.
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Affiliation(s)
- Julia Imkampe
- Department of Plant Biochemistry (ZMBP), Eberhard-Karls-University, 72076 Tübingen, Germany
| | - Thierry Halter
- Department of Plant Biochemistry (ZMBP), Eberhard-Karls-University, 72076 Tübingen, Germany
| | - Shuhua Huang
- State Key Laboratory of Crop Stress Biology in Arid Areas, College of Horticulture, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Sarina Schulze
- Department of Plant Biochemistry (ZMBP), Eberhard-Karls-University, 72076 Tübingen, Germany
| | - Sara Mazzotta
- Department of Plant Biochemistry (ZMBP), Eberhard-Karls-University, 72076 Tübingen, Germany
| | - Nikola Schmidt
- Department of Plant Biochemistry (ZMBP), Eberhard-Karls-University, 72076 Tübingen, Germany
| | - Raffaele Manstretta
- Department of Plant Biochemistry (ZMBP), Eberhard-Karls-University, 72076 Tübingen, Germany
| | - Sandra Postel
- Department of Plant Biochemistry (ZMBP), Eberhard-Karls-University, 72076 Tübingen, Germany
| | - Michael Wierzba
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, Arizona 85721
| | - Yong Yang
- State Key Laboratory of Crop Stress Biology in Arid Areas, College of Horticulture, Northwest A&F University, Yangling, Shaanxi 712100, China
| | | | - Mark Stahl
- Analytics Department of the ZMBP, Eberhard-Karls-University, 72076 Tübingen, Germany
| | - Cyril Zipfel
- The Sainsbury Laboratory, Norwich NR4 7UH, United Kingdom
| | - Michael B Goshe
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh, North Carolina 27695
| | - Steven Clouse
- Department of Horticultural Science, North Carolina State University, Raleigh, North Carolina 27695
| | - Sacco C de Vries
- Laboratory of Biochemistry, Wageningen University, Wageningen 6708 WE, The Netherlands
| | - Frans Tax
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, Arizona 85721
| | - Xiaofeng Wang
- State Key Laboratory of Crop Stress Biology in Arid Areas, College of Horticulture, Northwest A&F University, Yangling, Shaanxi 712100, China
| | - Birgit Kemmerling
- Department of Plant Biochemistry (ZMBP), Eberhard-Karls-University, 72076 Tübingen, Germany
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