AtNHX5 and AtNHX6: Roles in protein transport

Qiu, Quan Sheng

doi:10.1080/15592324.2016.1184810

Cited by 15 publications

(10 citation statements)

References 21 publications

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“…This demonstrates that they have the same function and so complement each other in the absence of either one of them. NHX5 and NHX6 regulate endosomal pH by preventing acidification through leakage of H + out of the compartments (Qiu, 2016a , b ), and regulate protein transport by controlling three distinct stages: the binding of vacuolar sorting receptor (VSR), recycling of VSRs and the subcellular localization of the SNARE complex (Ashnest et al, 2015 ; Reguera et al, 2015 ; Qiu, 2016a , b ; Wu et al, 2016 ), and they participate in protein storage vacuole formation as well as in retromer-dependent vacuolar trafficking through their cytosolic C-terminal. Deletion of this C-terminal in NHX6 failed to rescue the nhx5nhx6 phenotype (Ashnest et al, 2015 ).…”

Section: Nhxs Regulate Intracellular Ph and Vesicle Trafficking Betwementioning

confidence: 99%

The Role of Na+ and K+ Transporters in Salt Stress Adaptation in Glycophytes

et al. 2017

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Ionic stress is one of the most important components of salinity and is brought about by excess Na+ accumulation, especially in the aerial parts of plants. Since Na+ interferes with K+ homeostasis, and especially given its involvement in numerous metabolic processes, maintaining a balanced cytosolic Na+/K+ ratio has become a key salinity tolerance mechanism. Achieving this homeostatic balance requires the activity of Na+ and K+ transporters and/or channels. The mechanism of Na+ and K+ uptake and translocation in glycophytes and halophytes is essentially the same, but glycophytes are more susceptible to ionic stress than halophytes. The transport mechanisms involve Na+ and/or K+ transporters and channels as well as non-selective cation channels. Thus, the question arises of whether the difference in salt tolerance between glycophytes and halophytes could be the result of differences in the proteins or in the expression of genes coding the transporters. The aim of this review is to seek answers to this question by examining the role of major Na+ and K+ transporters and channels in Na+ and K+ uptake, translocation and intracellular homeostasis in glycophytes. It turns out that these transporters and channels are equally important for the adaptation of glycophytes as they are for halophytes, but differential gene expression, structural differences in the proteins (single nucleotide substitutions, impacting affinity) and post-translational modifications (phosphorylation) account for the differences in their activity and hence the differences in tolerance between the two groups. Furthermore, lack of the ability to maintain stable plasma membrane (PM) potentials following Na+-induced depolarization is also crucial for salt stress tolerance. This stable membrane potential is sustained by the activity of Na+/H+ antiporters such as SOS1 at the PM. Moreover, novel regulators of Na+ and K+ transport pathways including the Nax1 and Nax2 loci regulation of SOS1 expression and activity in the stele, and haem oxygenase involvement in stabilizing membrane potential by activating H+-ATPase activity, favorable for K+ uptake through HAK/AKT1, have been shown and are discussed.

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Section: Nhxs Regulate Intracellular Ph and Vesicle Trafficking Betwementioning

confidence: 99%

The Role of Na+ and K+ Transporters in Salt Stress Adaptation in Glycophytes

et al. 2017

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“…A recent report showed that NHX5 and NHX6 might regulate auxin transport across the ER via the pH gradient created by their transport activity (Fan et al, 2018). These results suggest that NHX5 and NHX6 facilitate Na + ,K + /H + exchange and may act as an H + leak system to regulate cellular pH homeostasis (Qiu, 2016a(Qiu, , 2016b.…”

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confidence: 92%

“…NHX5 and NHX6 proteins share high sequence similarity, are genetically redundant, and both localize in the endosomal compartments, including the Golgi, TGN, and PVC/MVB (Yokoi et al, 2002;Bassil et al, 2011a;Reguera et al, 2015;Wang et al, 2015). NHX5 and NHX6 are required for the transport of seed storage proteins into the protein storage vacuole (Reguera et al, 2015;Qiu, 2016b;Wu et al, 2016). Using organelle specific pHluorin-based pH sensors, Reguera et al (2015) found that the nhx5 nhx6 mutant had reduced pH in Golgi, TGN, and the late PVC.…”

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confidence: 99%

K⁺ Efflux Antiporters 4, 5, and 6 Mediate pH and K⁺ Homeostasis in Endomembrane Compartments

et al. 2018

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The endomembrane system, which sorts proteins and membranes through the secretory and endocytic pathways, is critical for cellular functions in eukary-otes (Otegui and Spitzer, 2008; Richter et al., 2009; Contento and Bassham, 2012). The plant endomembrane system comprises the endoplasmic reticulum (ER), Golgi complex, trans-Golgi network (TGN), prevacuolar compartment (PVC)/multivesicular bodies (MVB), and vacuoles (Contento and Bassham, 2012). The endomembrane system, by enabling protein modification and sorting, plays important roles in cell polarity, cytokinesis, cell wall formation, signaling, and stress tolerance (

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“…They are essential for cellular ion and pH homeostasis and play significant roles in diverse cellular processes (Bassil, Coku, & Blumwald, ; Chanroj et al, ; Pardo, Cubero, Leidi, & Quintero, ; Qiu, ; Reguera, Bassil, & Blumwald, ). AtNHX5 and AtNHX6, which share high sequence similarity (78.7%), are endosomal NHX antiporters that are localized in the Golgi, trans‐Golgi network (TGN), and prevacuolar compartment (PVC) (Pardo et al, ; Qiu, ; Qiu, ; Reguera et al, ; Yokoi et al, ). Studies showed that nhx5 nhx6 double mutant was defective in development, having smaller rosettes and shorter seedlings (Bassil et al, ; Wang, Wu, Liu, & Qiu, ; Wu, Ebine, Ueda, & Qiu, ).…”

Section: Introductionmentioning

confidence: 99%

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

Fan

Zhao

et al. 2018

Plant Cell & Environment

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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 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.

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AtNHX5 and AtNHX6: Roles in protein transport

Cited by 15 publications

References 21 publications

The Role of Na+ and K+ Transporters in Salt Stress Adaptation in Glycophytes

The Role of Na+ and K+ Transporters in Salt Stress Adaptation in Glycophytes

K⁺ Efflux Antiporters 4, 5, and 6 Mediate pH and K⁺ Homeostasis in Endomembrane Compartments

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

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AtNHX5 and AtNHX6: Roles in protein transport

Cited by 15 publications

References 21 publications

The Role of Na+ and K+ Transporters in Salt Stress Adaptation in Glycophytes

The Role of Na+ and K+ Transporters in Salt Stress Adaptation in Glycophytes

K+ Efflux Antiporters 4, 5, and 6 Mediate pH and K+ Homeostasis in Endomembrane Compartments

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

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K⁺ Efflux Antiporters 4, 5, and 6 Mediate pH and K⁺ Homeostasis in Endomembrane Compartments

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