9G11

sugar/H+ symporter STP6 in inward occluded conformation with glucose bound

Summary for 9G11

• Entry DOI: 10.2210/pdb9g11/pdb
• Descriptor: Sugar transport protein 6, beta-D-glucopyranose, CHOLESTEROL HEMISUCCINATE (3 entities in total)
• Functional Keywords: sugar transporter, stp, mfs, membrane protein
• Biological source: Arabidopsis thaliana (thale cress)
• Total number of polymer chains: 1
• Total formula weight: 57591.94

Authors

Andersen, C.G.,Bavnhoej, L.,Pedersen, B.P. (deposition date: 2024-07-09, release date: 2024-08-14, Last modification date: 2025-08-27)

Primary citation

Andersen, C.G.,Bavnhoj, L.,Brag, S.,Bohush, A.,Chrenkova, A.,Driller, J.H.,Pedersen, B.P.
Comparative analysis of STP6 and STP10 unravels molecular selectivity in sugar transport proteins.
Proc.Natl.Acad.Sci.USA, 122:e2417370122-e2417370122, 2025

PubMed Abstract: The distribution of sugars is crucial for plant energy, signaling, and defense mechanisms. Sugar Transport Proteins (STPs) are Sugar Porters (SPs) that mediate proton-driven cellular uptake of glucose. Some STPs also transport fructose, while others remain highly selective for only glucose. What determines this selectivity, allowing STPs to distinguish between compounds with highly similar chemical composition, remains unknown. Here, we present the structure of STP6 in an inward-occluded conformational state with glucose bound and demonstrate its role as both a glucose and fructose transporter. We perform a comparative analysis of STP6 with the glucose-selective STP10 using in vivo and in vitro systems, demonstrating how different experimental setups strongly influence kinetic transport properties. We analyze the properties of the monosaccharide binding site and show that the position of a single methyl group in the binding site is sufficient to shuffle glucose and fructose specificity, providing detailed insights into the fine-tuned dynamics of affinity-induced specificity for sugar uptake. Altogether, these findings enhance our understanding of sugar selectivity in STPs and more broadly SP proteins.

PubMed: 40279393
DOI: 10.1073/pnas.2417370122

Experimental method

X-RAY DIFFRACTION (3.2 Å)