PLANTPLASMAMEMBRANEH⁺-ATPases: Powerhouses for Nutrient Uptake

Abstract

Most transport proteins in plant cells are energized by electrochemical gradients of protons across the plasma membrane. The formation of these gradients is due to the action of plasma membrane H+ pumps fuelled by ATP. The plasma membrane H+-ATPases share a membrane topography and general mechanism of action with other P-type ATPases, but differ in regulatory properties. Recent advances in the field include the identification of the complete H+-ATPase gene family in Arabidopsis, analysis of H+-ATPase function by the methods of reverse genetics, an improved understanding of the posttranslational regulation of pump activity by 14-3-3 proteins, novel insights into the H+ transport mechanism, and progress in structural biology. Furthermore, the elucidation of the three-dimensional structure of a related Ca2+ pump has implications for understanding of structure-function relationships for the plant plasma membrane H+-ATPase.

H+‐pyrophosphatase IbVP1 promotes efficient iron use in sweet potato [Ipomoea batatas (L.) Lam.]

“…Changes in the rhizosphere represent a central mechanism in plant mineral nutrition, contributing to nutrient solubility and proton‐motive force (Li et al ., 2015; Palmgren, 2001; Palmgren, 1998; Santi and Schmidt, 2009; Zhu et al ., 2009). The increase in root iron precipitation, Fe content and FCR activity in the IA lines demonstrated regulation of Fe uptake, which is associated with the up‐regulation of key genes such as FRO2 , IRT and FIT involved in Fe acquisition (Figure 8).…”

The Binding Site for Regulatory 14-3-3 Protein in Plant Plasma Membrane H+-ATPase

“…Most secondary transporters in plant cells depend upon the activity of the plasma membrane H ϩ -ATPase, which is essential for generating the electrochemical gradient across the plasma membrane (for a review, see Ref. 14), and it has therefore generated considerable interest that 14-3-3 proteins have appeared as positive regulators of this proton pump (15).…”

Modulation of iron responsive gene expression and enzymatic activities in response to changes of the iron nutritional status in Cucumis sativus L.

“…From these experiments it is clear that the whole iron deficiency response is under the same gross control and that supply of iron rapidly de-induces the expression of these transcripts altogether (Fig. 3B), greater for the CsFRO1 and CsIRT1 (they serve specifically for iron uptake), which reach the level seen in the control roots within 48 h, than for the CsHA1 and Cspepc1, that are less specific and also serve for other important cellular functions (Chollet et al, 1996;Palmgren, 2001). A further possible explanation of this different response could relay on the fact that for CsFRO1 and CsIRT1 we can assume a primary coordinate regulation, both local and systemic in response to a direct event (presence or absence of iron).…”

“…Enhancement of H + efflux, due to an increase in a P-type H + -ATPase activity in response to iron deprivation, was demonstrated in many Strategy I plants (Schmidt, 1999;Zocchi, 2006). A multigene family encoding different isoforms for H + -ATPase and tissue specific expression patterns have been demonstrated (Palmgren, 2001;Dell'Orto et al, 2002;Santi et al, 2005). After mobilization and reduction, the ferrous form, the unique form to be absorbed by these plants, needs to be taken up across the plasma membrane by a specific iron transporter (IRT1) that has been characterized in A. thaliana (Eide et al, 1996) and successively in pea and tomato (Cohen et al, 1998;Eckhardt et al, 2001).…”