Structure and Function of an Arabidopsis thaliana Sulfate Transporter

Authors

Lie Wang
Kehan Chen
Ming Zhou

Publication Date

7-22-2021

Journal

Nature Communications

DOI

10.1038/s41467-021-24778-2

PMID

34294705

PMCID

PMC8298490

PubMedCentral® Posted Date

7-22-2021

PubMedCentral® Full Text Version

Post-print

Published Open-Access

yes

Keywords

Anion Transport Proteins, Arabidopsis, Arabidopsis Proteins, Binding Sites, Cryoelectron Microscopy, Glutamic Acid, Models, Molecular, Protein Interaction Domains and Motifs, Protein Multimerization, Recombinant Proteins, Static Electricity, Sulfate Transporters, Sulfates, Cryoelectron microscopy, Permeation and transport, Plant transporters

Abstract

Plant sulfate transporters (SULTR) mediate absorption and distribution of sulfate (SO42−) and are essential for plant growth; however, our understanding of their structures and functions remains inadequate. Here we present the structure of a SULTR from Arabidopsis thaliana, AtSULTR4;1, in complex with SO42− at an overall resolution of 2.8 Å. AtSULTR4;1 forms a homodimer and has a structural fold typical of the SLC26 family of anion transporters. The bound SO42− is coordinated by side-chain hydroxyls and backbone amides, and further stabilized electrostatically by the conserved Arg393 and two helix dipoles. Proton and SO42− are co-transported by AtSULTR4;1 and a proton gradient significantly enhances SO42− transport. Glu347, which is ~7 Å from the bound SO42−, is required for H+-driven transport. The cytosolic STAS domain interacts with transmembrane domains, and deletion of the STAS domain or mutations to the interface compromises dimer formation and reduces SO42− transport, suggesting a regulatory function of the STAS domain.

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