Publications

• Molecular mechanism of sugar transport in plants unveiled by structures of glucose/H+ symporter STP10.

  Bavnhoj L., Paulsen P.A., Flores-Canales J.C., Schiott B., Pedersen B.P.

  Sugars are essential sources of energy and carbon and also function as key signalling molecules in plants. Sugar transport proteins (STP) are proton-coupled symporters responsible for uptake of glucose from the apoplast into plant cells. They are integral to organ development in symplastically iso ... >> More

  Sugars are essential sources of energy and carbon and also function as key signalling molecules in plants. Sugar transport proteins (STP) are proton-coupled symporters responsible for uptake of glucose from the apoplast into plant cells. They are integral to organ development in symplastically isolated tissues such as seed, pollen and fruit. Additionally, STPs play a vital role in plant responses to stressors such as dehydration and prevalent fungal infections like rust and mildew. Here we present a structure of Arabidopsis thaliana STP10 in the inward-open conformation at 2.6 Å resolution and a structure of the outward-occluded conformation at improved 1.8 Å resolution, both with glucose and protons bound. The two structures describe key states in the STP transport cycle. Together with molecular dynamics simulations that establish protonation states and biochemical analysis, they pinpoint structural elements, conserved in all STPs, that clarify the basis of proton-to-glucose coupling. These results advance our understanding of monosaccharide uptake, which is essential for plant organ development, and set the stage for bioengineering strategies in crops. << Less

  Nat. Plants 7:1409-1419(2021) [PubMed] [EuropePMC]

• STP10 encodes a high-affinity monosaccharide transporter and is induced under low-glucose conditions in pollen tubes of Arabidopsis.

  Rottmann T., Zierer W., Subert C., Sauer N., Stadler R.

  Pollen tubes are fast growing, photosynthetically inactive cells. Their energy demand is covered by specific transport proteins in the plasma membrane that mediate the uptake of sugars. Here we report on the functional characterization of AtSTP10, a previously uncharacterized member of the SUGAR T ... >> More

  Pollen tubes are fast growing, photosynthetically inactive cells. Their energy demand is covered by specific transport proteins in the plasma membrane that mediate the uptake of sugars. Here we report on the functional characterization of AtSTP10, a previously uncharacterized member of the SUGAR TRANSPORT PROTEIN family. Heterologous expression of STP10 cDNA in yeast revealed that the encoded protein catalyses the high-affinity uptake of glucose, galactose and mannose. The transporter is sensitive to uncouplers of transmembrane proton gradients, indicating that the protein acts as a hexose-H(+)symporter. Analyses of STP10 mRNA and STP10 promoter-reporter gene studies revealed a sink-specific expression pattern of STP10 in primordia of lateral roots and in pollen tubes. This restriction to sink organs is mediated by intragenic regions of STP10 qPCR analyses with cDNA of in vitro grown pollen tubes showed that STP10 expression was down-regulated in the presence of 50mM glucose. However, in pollen tubes of glucose-insensitive plants, which lack the glucose sensor hexokinase1 (HXK1), no glucose-induced down-regulation of STP10 expression was detected. A stp10T-DNA insertion line developed normally, which may point towards functional redundancy. The data presented in this paper indicate that a high-affinity glucose uptake system is induced in growing pollen tubes under low glucose conditions and that this regulation may occur through the hexokinase pathway. << Less

  J. Exp. Bot. 67:2387-2399(2016) [PubMed] [EuropePMC]

  This publication is cited by 2 other entries.

• Crystal structure of the plant symporter STP10 illuminates sugar uptake mechanism in monosaccharide transporter superfamily.

  Paulsen P.A., Custodio T.F., Pedersen B.P.

  Plants are dependent on controlled sugar uptake for correct organ development and sugar storage, and apoplastic sugar depletion is a defense strategy against microbial infections like rust and mildew. Uptake of glucose and other monosaccharides is mediated by Sugar Transport Proteins, proton-coupl ... >> More

  Plants are dependent on controlled sugar uptake for correct organ development and sugar storage, and apoplastic sugar depletion is a defense strategy against microbial infections like rust and mildew. Uptake of glucose and other monosaccharides is mediated by Sugar Transport Proteins, proton-coupled symporters from the Monosaccharide Transporter (MST) superfamily. We present the 2.4 Å structure of Arabidopsis thaliana high affinity sugar transport protein, STP10, with glucose bound. The structure explains high affinity sugar recognition and suggests a proton donor/acceptor pair that links sugar transport to proton translocation. It contains a Lid domain, conserved in all STPs, that locks the mobile transmembrane domains through a disulfide bridge, and creates a protected environment which allows efficient coupling of the proton gradient to drive sugar uptake. The STP10 structure illuminates fundamental principles of sugar transport in the MST superfamily with implications for both plant antimicrobial defense, organ development and sugar storage. << Less

  Nat. Commun. 10:407-407(2019) [PubMed] [EuropePMC]

  This publication is cited by 2 other entries.