Identification of Arabidopsis thaliana NRT1/PTR FAMILY (NPF) proteins capable of transporting plant hormones

Abstract

NRT1/PTR FAMILY (NPF) proteins were originally identified as nitrate or di/tri-peptide transporters. Recent studies revealed that this transporter family also transports the plant hormones auxin (indole-3-acetic acid), abscisic acid (ABA), and gibberellin (GA), as well as secondary metabolites (glucosinolates). We developed modified yeast two-hybrid systems with receptor complexes for GA and jasmonoyl-isoleucine (JA-Ile), to detect GA and JA-Ile transport activities of proteins expressed in the yeast cells. Using these GA and JA-Ile systems as well as the ABA system that we had introduced previously, we determined the capacities of Arabidopsis NPFs to transport these hormones. Several NPFs induced the formation of receptor complexes under relatively low hormone concentrations. Hormone transport activities were confirmed for some NPFs by direct analysis of hormone uptake of yeast cells by liquid chromatography-tandem mass spectrometry. Our results suggest that at least some NPFs could function as hormone transporters.

Environmental nitrate signals through abscisic acid in the root tip

“…Although NRT2 transporters appear to be specific for nitrate, many NPF proteins transport substrates other than, or in addition to, nitrate. 18,19 Nonetheless, there are many different ways nitrate can enter an Arabidopsis cell. Expression of characterized transporters in Arabidopsis is restricted to specific cells and tissues, allowing the plant fine control over nitrate movement both into and within the plant.…”

“…Recently, several ABA transporters have been identified, many of which also transport other substrates. 19,[47][48][49][50] Increasing the concentration of one substrate is likely to have effects on the transport of the others. For AtNPF4.1, transport of the gibberellin, GA 3 , competes with ABA transport.…”

TEMPRANILLO Reveals the Mesophyll as Crucial for Epidermal Trichome Formation

“…Plant hormones are active in plant tissues at very low concentration; therefore the synthesis, transport and signaling of hormones are precisely controlled processes (Chiba et al, 2015). Recent studies suggest that GA movement and distribution might be regulated by a group of GA transporters (Chiba et al, 2015;Saito et al, 2015).…”

“…Recent studies suggest that GA movement and distribution might be regulated by a group of GA transporters (Chiba et al, 2015;Saito et al, 2015). The NITRATE TRANSPORTER 1/PEPTIDE TRANSPORTER FAMILY (NPF) is a family of proteins initially identified as nitrate or peptide transporters (Tsay et al, 2007;Léran et al, 2014), and was later found to also transport hormones such as auxin and abcisic acid (Krouk et al, 2010;Kanno et al, 2012).…”

Long-distance transport of endogenous gibberellins in Arabidopsis

“…9 Recently, biochemical studies in heterologous systems allowed the identification of several GA transporters, belonging to the NITRATE TRANSPORTER 1/PEPTIDE TRANSPORTER FAMILY (NPF). [15][16][17] The NPFs represent a large family of membrane proteins which transport a wide array of compounds including nitrate, peptides, glucosinolates and phytohormones. 18 Although not demonstrated, it is tempting to speculate that these multifunctional transporters may contribute in the translocation of GA 12 from parenchyma cells to the vessels.…”