This Article Full Text Full Text (PDF) PPT slides of all figures Supplemental Data All Versions of this Article: 21/2/622    most recent tpc.108.061994v1 Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Web of Science (5) Citing Articles via Google Scholar Google Scholar Articles by Lee, H. K. Articles by Kim, W. T. Search for Related Content PubMed PubMed Citation Articles by Lee, H. K. Articles by Kim, W. T. Agricola Articles by Lee, H. K. Articles by Kim, W. T.

Drought Stress-Induced Rma1H1, a RING Membrane-Anchor E3 Ubiquitin Ligase Homolog, Regulates Aquaporin Levels via Ubiquitination in Transgenic Arabidopsis Plants^[C],[W]

^a Department of Integrative Bioscience and Biotechnology, Division of Molecular and Life Science, Pohang University of Science and Technology, Pohang 790-784, Korea
^b Department of Biology, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Korea

³ Address correspondence to ihhwang{at}postech.ac.kr or wtkim{at}yonsei.ac.kr.

Ubiquitination is involved in a variety of biological processes, but the exact role of ubiquitination in abiotic responses is not clearly understood in higher plants. Here, we investigated Rma1H1, a hot pepper (Capsicum annuum) homolog of a human RING membrane-anchor 1 E3 ubiquitin (Ub) ligase. Bacterially expressed Rma1H1 displayed E3 Ub ligase activity in vitro. Rma1H1 was rapidly induced by various abiotic stresses, including dehydration, and its overexpression in transgenic Arabidopsis thaliana plants conferred strongly enhanced tolerance to drought stress. Colocalization experiments with marker proteins revealed that Rma1H1 resides in the endoplasmic reticulum (ER) membrane. Overexpression of Rma1H1 in Arabidopsis inhibited trafficking of an aquaporin isoform PIP2;1 from the ER to the plasma membrane and reduced PIP2;1 levels in protoplasts and transgenic plants. This Rma1H1-induced reduction of PIP2;1 was inhibited by MG132, an inhibitor of the 26S proteasome. Furthermore, Rma1H1 interacted with PIP2;1 in vitro and ubiquitinated it in vivo. Similar to Rma1H1, Rma1, an Arabidopsis homolog of Rma1H1, localized to the ER, and its overexpression reduced the PIP2;1 protein level and inhibited trafficking of PIP2;1 from the ER to the plasma membrane in protoplasts. In addition, reduced expression of Rma homologs resulted in the increased level of PIP2;1 in protoplasts. We propose that Rma1H1 and Rma1 play a critical role in the downregulation of plasma membrane aquaporin levels by inhibiting aquaporin trafficking to the plasma membrane and subsequent proteasomal degradation as a response to dehydration in transgenic Arabidopsis plants.

This article has been cited by other articles:

				J. Ning, X. Li, L. M. Hicks, and L. Xiong A Raf-Like MAPKKK Gene DSM1 Mediates Drought Resistance through Reactive Oxygen Species Scavenging in Rice Plant Physiology, February 1, 2010; 152(2): 876 - 890. [Abstract] [Full Text] [PDF]

				Y.-F. Chen, L.-Q. Li, Q. Xu, Y.-H. Kong, H. Wang, and W.-H. Wu The WRKY6 Transcription Factor Modulates PHOSPHATE1 Expression in Response to Low Pi Stress in Arabidopsis PLANT CELL, November 1, 2009; 21(11): 3554 - 3566. [Abstract] [Full Text] [PDF]