Structure of Bor1 supports an elevator transport mechanism for SLC4 anion exchangers.
Proc Natl Acad Sci U S A
; 113(38): 10542-6, 2016 09 20.
Article
em En
| MEDLINE
| ID: mdl-27601653
ABSTRACT
Boron 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-Å 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.
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MEDLINE
Assunto principal:
Conformação Proteica
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Antiporters
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Simportadores de Sódio-Bicarbonato
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Proteínas de Arabidopsis
Idioma:
En
Ano de publicação:
2016
Tipo de documento:
Article