5l25
From Proteopedia
Crystal Structure of Arabidopsis thaliana Bor1
Structural highlights
Function[BOR1_ARATH] Efflux-type boron transporter for xylem loading, responsive of boron translocation from roots to shoots under boron limitation. Under boron excess, BOR1 is transferred from the plasma membrane via the endosomes to the vacuole for degradation. Boron is essential for maintaining the integrity of plants cell walls.[1] [2] Publication Abstract from PubMedBoron is essential for plant growth because of its incorporation into plant cell walls; however, in excess it is toxic to plants. Boron transport and homeostasis in plants is regulated in part by the borate efflux transporter Bor1, a member of the solute carrier (SLC) 4 transporter family with homology to the human bicarbonate transporter Band 3. Here, we present the 4.1-A resolution crystal structure of Arabidopsis thaliana Bor1. The structure displays a dimeric architecture in which dimerization is mediated by centralized Gate domains. Comparisons with a structure of Band 3 in an outward-open state reveal that the Core domains of Bor1 have rotated inwards to achieve an occluded state. Further structural comparisons with UapA, a xanthine transporter from the nucleobase-ascorbate transporter family, show that the downward pivoting of the Core domains relative to the Gate domains may access an inward-open state. These results suggest that the SLC4, SLC26, and nucleobase-ascorbate transporter families all share an elevator transport mechanism in which alternating access is provided by Core domains that carry substrates across a membrane. Structure of Bor1 supports an elevator transport mechanism for SLC4 anion exchangers.,Thurtle-Schmidt BH, Stroud RM Proc Natl Acad Sci U S A. 2016 Sep 6. pii: 201612603. PMID:27601653[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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