8bb6

Crystal structure of Arabidopsis thaliana sucrose transporter SUC1Crystal structure of Arabidopsis thaliana sucrose transporter SUC1

Structural highlights

8bb6 is a 2 chain structure with sequence from Arabidopsis thaliana. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:	X-ray diffraction, Resolution 2.68Å
Resources:	FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Function

SUC1_ARATH Responsible for the transport of sucrose into the cell, with the concomitant uptake of protons (symport system). This transport is both voltage- and energy-dependent. Can also transport other glucosides such as maltose, alpha-phenylglucoside and beta-phenylglucoside. May also transport biotin. Required for normal pollen germination and anthocyanin accumulation induced by sucrose.^[1] ^[2] ^[3] ^[4]

Publication Abstract from PubMed

Sucrose import from photosynthetic tissues into the phloem is mediated by transporters from the low-affinity sucrose transporter family (SUC/SUT family). Furthermore, sucrose redistribution to other tissues is driven by phloem sap movement, the product of high turgor pressure created by this import activity. Additionally, sink organs such as fruits, cereals and seeds that accumulate high concentrations of sugar also depend on this active transport of sucrose. Here we present the structure of the sucrose-proton symporter, Arabidopsis thaliana SUC1, in an outward open conformation at 2.7 A resolution, together with molecular dynamics simulations and biochemical characterization. We identify the key acidic residue required for proton-driven sucrose uptake and describe how protonation and sucrose binding are strongly coupled. Sucrose binding is a two-step process, with initial recognition mediated by the glucosyl moiety binding directly to the key acidic residue in a stringent pH-dependent manner. Our results explain how low-affinity sucrose transport is achieved in plants, and pinpoint a range of SUC binders that help define selectivity. Our data demonstrate a new mode for proton-driven symport with links to cation-driven symport and provide a broad model for general low-affinity transport in highly enriched substrate environments.

Structure and sucrose binding mechanism of the plant SUC1 sucrose transporter.,Bavnhoj L, Driller JH, Zuzic L, Stange AD, Schiott B, Pedersen BP Nat Plants. 2023 Jun;9(6):938-950. doi: 10.1038/s41477-023-01421-0. Epub 2023 May , 15. PMID:37188854^[5]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

References

↑ Stadler R, Truernit E, Gahrtz M, Sauer N. The AtSUC1 sucrose carrier may represent the osmotic driving force for anther dehiscence and pollen tube growth in Arabidopsis. Plant J. 1999 Aug;19(3):269-78. PMID:10476074 doi:10.1046/j.1365-313x.1999.00527.x
↑ Sivitz AB, Reinders A, Ward JM. Arabidopsis sucrose transporter AtSUC1 is important for pollen germination and sucrose-induced anthocyanin accumulation. Plant Physiol. 2008 May;147(1):92-100. PMID:18359840 doi:10.1104/pp.108.118992
↑ Sauer N, Stolz J. SUC1 and SUC2: two sucrose transporters from Arabidopsis thaliana; expression and characterization in baker's yeast and identification of the histidine-tagged protein. Plant J. 1994 Jul;6(1):67-77. PMID:7920705 doi:10.1046/j.1365-313x.1994.6010067.x
↑ Zhou J, Theodoulou F, Sauer N, Sanders D, Miller AJ. A kinetic model with ordered cytoplasmic dissociation for SUC1, an Arabidopsis H+/sucrose cotransporter expressed in Xenopus oocytes. J Membr Biol. 1997 Sep 15;159(2):113-25. PMID:9307438 doi:10.1007/s002329900275
↑ Bavnhøj L, Driller JH, Zuzic L, Stange AD, Schiøtt B, Pedersen BP. Structure and sucrose binding mechanism of the plant SUC1 sucrose transporter. Nat Plants. 2023 May 15. PMID:37188854 doi:10.1038/s41477-023-01421-0

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OCA

[1] Stadler R, Truernit E, Gahrtz M, Sauer N. The AtSUC1 sucrose carrier may represent the osmotic driving force for anther dehiscence and pollen tube growth in Arabidopsis. Plant J. 1999 Aug;19(3):269-78. PMID:10476074 doi:10.1046/j.1365-313x.1999.00527.x

[2] Sivitz AB, Reinders A, Ward JM. Arabidopsis sucrose transporter AtSUC1 is important for pollen germination and sucrose-induced anthocyanin accumulation. Plant Physiol. 2008 May;147(1):92-100. PMID:18359840 doi:10.1104/pp.108.118992

[3] Sauer N, Stolz J. SUC1 and SUC2: two sucrose transporters from Arabidopsis thaliana; expression and characterization in baker's yeast and identification of the histidine-tagged protein. Plant J. 1994 Jul;6(1):67-77. PMID:7920705 doi:10.1046/j.1365-313x.1994.6010067.x

[4] Zhou J, Theodoulou F, Sauer N, Sanders D, Miller AJ. A kinetic model with ordered cytoplasmic dissociation for SUC1, an Arabidopsis H+/sucrose cotransporter expressed in Xenopus oocytes. J Membr Biol. 1997 Sep 15;159(2):113-25. PMID:9307438 doi:10.1007/s002329900275

[5] Bavnhøj L, Driller JH, Zuzic L, Stange AD, Schiøtt B, Pedersen BP. Structure and sucrose binding mechanism of the plant SUC1 sucrose transporter. Nat Plants. 2023 May 15. PMID:37188854 doi:10.1038/s41477-023-01421-0

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