NHX antiporters regulate the pH of endoplasmic reticulum and auxin-mediated development Journal Article

Author(s): Fan, Ligang; Zhao, Lei; Hu, Wei; Li, Weina; Novák, Ondřej; Strnad, Miroslav; Simon, Sibu; Friml, Jiří; Shen, Jinbo; Jiang, Liwen; Qiu, Quan-Sheng
Article Title: NHX antiporters regulate the pH of endoplasmic reticulum and auxin-mediated development
Affiliation IST Austria
Abstract: AtNHX5 and AtNHX6 are endosomal Na+,K+/H+ antiporters that are critical for growth and development in Arabidopsis, but the mechanism behind their action remains unknown. Here, we report that AtNHX5 and AtNHX6, functioning as H+ leak, control auxin homeostasis and auxin-mediated development. We found that nhx5 nhx6 exhibited growth variations of auxin-related defects. We further showed that nhx5 nhx6 was affected in auxin homeostasis. Genetic analysis showed that AtNHX5 and AtNHX6 were required for the function of the ER-localized auxin transporter PIN5. Although AtNHX5 and AtNHX6 were co-localized with PIN5 at ER, they did not interact directly. Instead, the conserved acidic residues in AtNHX5 and AtNHX6, which are essential for exchange activity, were required for PIN5 function. AtNHX5 and AtNHX6 regulated the pH in ER. Overall, AtNHX5 and AtNHX6 may regulate auxin transport across the ER via the pH gradient created by their transport activity. H+-leak pathway provides a fine-tuning mechanism that controls cellular auxin fluxes.
Keywords: Development; Arabidopsis; Auxin; PIN5; endosomal Na+; K+/H+ antiporters; AtNHX5; AtNHX6; pH
Journal Title: Plant, Cell and Environment
Volume: 41
ISSN: 1365-3040
Publisher: Wiley-Blackwell  
Date Published: 2018-05-01
Start Page: 850
End Page: 864
DOI: 10.1111/pce.13153
Notes: This work was supported by the National Natural Science Foundation of China (31571464, 31371438 and 31070222 to Q.S.Q.), the National Basic Research Program of China (973 project, 2013CB429904 to Q.S.Q.), the Research Fund for the Doctoral Program of Higher Education of China (20130211110001 to Q.S.Q.), the Ministry of Education, Youth and Sports of the Czech Republic (the National Program for Sustainability I, LO1204), and The Czech Science Foundation GAČR (GA13–40637S) to JF. We thank Dr. Tom J. Guilfoyle for DR5::GUS line and Dr. Jia Li for pBIB‐RFP vector and DR5::GFP line. We thank Liping Guan and Yang Zhao for their help with the confocal microscope assay.
Open access: no