Na+, K+/H+ antiporters regulate the pH of endoplasmic reticulum and auxin-mediated development

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Authors	FAN L.G. ZHAO L. HU W. LI W.N. NOVAK O. STRNAD M. SIMON Sibu FRIML J. SHEN J.B. JIANG L.W. QIU Q.S.
Year of publication	2018
Type	Article in Periodical
Magazine / Source	Plant, cell and environment
MU Faculty or unit	Central European Institute of Technology
Citation
Doi	http://dx.doi.org/10.1111/pce.13153
Keywords	Arabidopsis; endosomal Na+K+/H+ antiporters; AtNHX5; AtNHX6; PIN5; pH
Description	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 auxinmediated 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 endoplasmic reticulum (ER)-localized auxin transporter PIN5. Although AtNHX5 and AtNHX6 were colocalized 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.
Related projects:	Genetické studie k identifikaci molekulárních mechanizmu bunecné polarity a auxinového transportu v rostlinách