title: SORTING NEXIN1 is required for modulating the trafficking and stability of the Arabidopsis IRON-REGULATED TRANSPORTER1.
abstract: Dicotyledonous plants growing under limited iron availability initiate a response resulting in the solubilization, reduction, and uptake of soil iron. The protein factors responsible for these steps are transmembrane proteins, suggesting that the intracellular trafficking machinery may be involved in iron acquisition. In search for components involved in the regulation of Arabidopsis thaliana iron deficiency responses, we identified the members of the SORTING NEXIN (SNX) protein family. SNX loss-of-function plants display enhanced susceptibility to iron deficiency in comparison to the wild type. The absence of SNX led to reduced iron import efficiency into the root. SNX1 showed partial colocalization with the principal root iron importer IRON-REGULATED TRANSPORTER1 (IRT1). In SNX loss-of-function plants, IRT1 protein levels were decreased compared with the wild type due to enhanced IRT1 degradation. This resulted in diminished amounts of the IRT1 protein at the plasma membrane. snx mutants exhibited enhanced iron deficiency responses compared with the wild type, presumably due to the lower iron uptake through IRT1. Our results reveal a role of SNX1 for the correct trafficking of IRT1 and, thus, for modulating the activity of the iron uptake machinery.
authors.affiliation: Institute of Botany, Heinrich-Heine University, D-40225 Duesseldorf, Germany.
authors.forename: Rumen
authors.initials: R
authors.lastname: Ivanov
authors.forename: Tzvetina
authors.initials: T
authors.lastname: Brumbarova
authors.forename: Ailisa
authors.initials: A
authors.lastname: Blum
authors.forename: Anna-Maria
authors.initials: AM
authors.lastname: Jantke
authors.forename: Claudia
authors.initials: C
authors.lastname: Fink-Straube
authors.forename: Petra
authors.initials: P
authors.lastname: Bauer
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology*; D027682:Cation Transport Proteins / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D007501:Iron / Q000378:metabolism; D009154:Mutation; D021381:Protein Transport; D058305:Sorting Nexins / Q000235:genetics / Q000502:physiology*
chemical_list: D029681:Arabidopsis Proteins; D027682:Cation Transport Proteins; C099651:IRT1 protein, Arabidopsis; C584750:SNX1 protein, Arabidopsis; D058305:Sorting Nexins; D007501:Iron