Structural insights into the elevator-like mechanism of the sodium/citrate symporter CitS
SCIE
SCOPUS
- Title
- Structural insights into the elevator-like mechanism of the sodium/citrate symporter CitS
- Authors
- KIM, Ji Won; KIM, Subin; LEE, Haerim; LEE, JIE OH; JIN, Mi Sun
- Date Issued
- 2017-05-31
- Publisher
- Nature Publishing Group
- Abstract
- The sodium-dependent citrate transporter of Klebsiella pneumoniae (KpCitS) belongs to the 2-hydroxycarboxylate transporter (2-HCT) family and allows the cell to use citrate as sole carbon and energy source in anaerobic conditions. Here we present crystal structures of KpCitS in citrate-bound outward-facing, citrate-bound asymmetric, and citrate-free inward-facing state. The structures reveal that the KpCitS dimerization domain remains stationary throughout the transport cycle due to a hydrogen bond network as well as extensive hydrophobic interactions. In contrast, its transport domain undergoes a ~35° rigid-body rotation and a ~17 Å translocation perpendicular to the membrane to expose the substrate-binding site alternately to either side of the membrane. Furthermore, homology models of two other 2-HCT proteins based on the KpCitS structure offer structural insights into their differences in substrate specificity at a molecular level. On the basis of our results and previous biochemical data, we propose that the activity of the 2-HCT CitS involves an elevator-like movement in which the transport domain itself traverses the lipid bilayer, carrying the substrate into the cell in a sodium-dependent manner.
- URI
- https://oasis.postech.ac.kr/handle/2014.oak/103081
- DOI
- 10.1038/s41598-017-02794-x
- ISSN
- 2045-2322
- Article Type
- Article
- Citation
- Scientific Reports, vol. 7, no. 1, page. 2548, 2017-05-31
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- There are no files associated with this item.
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