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

By Laust Bavnhøj, P. A. Paulsen, J. C. Flores-Canales, B. Schiøtt, B. P. Pedersen. 2021

50 citations recorded by the source corpus.

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. Sugar transport proteins (STPs) that are responsible for glucose uptake in plant cells play fundamental roles in plant growth, development and stress responses. High-resolution structures of Arabidopsis STP10 with glucose and protons bound are now resolved at two conformations, outward-occluded and inward-open, providing a general model for proton/glucose symport in STPs.

Subfields: Materials Chemistry, Molecular Biology, Plant Science

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In Materials Chemistry

1. Diego del Alamo
2. Jens Meiler
3. Davide Sala
4. Hassane S. Mchaourab

In Molecular Biology

1. Diego del Alamo
2. Jens Meiler
3. Davide Sala
4. Hassane S. Mchaourab
5. Björn Wallner
6. David Baker

Citations in the corpus

• Sampling alternative conformational states of transporters and receptors with AlphaFold2 (2022, background): “…characterized in the literature ( Drew and Boudker, 2016 ), including rocking-bundle (LAT1, Yan et al., 2019 ; Yan et al., 2021 ; ZnT8, Xue et al., 2020 ), rocker-switch (MCT1, Wang et al., 2021 ; STP10, Bavnhøj et al., 2021 ), and elevator (ASCT2, Garibsingh et al., 2021 ; Garaeva et al., 2019 ).”