7EGL

Bicarbonate transporter complex SbtA-SbtB bound to HCO3-

7EGL の概要

• エントリーDOI: 10.2210/pdb7egl/pdb
• 分子名称: Sodium-dependent bicarbonate transporter SbtA, Membrane-associated protein SbtB, BICARBONATE ION, ... (5 entities in total)
• 機能のキーワード: bicarbonate transporter, ccm, allosteric inhibition, photosynthesis, transport protein
• 由来する生物種: Synechocystis sp. (strain PCC 6803 / Kazusa); 詳細
• タンパク質・核酸の鎖数: 2
• 化学式量合計: 51777.06

構造登録者

Fang, S.,Huang, X.,Zhang, X.,Zhang, P. (登録日: 2021-03-24, 公開日: 2021-05-26, 最終更新日: 2024-11-13)

主引用文献

Fang, S.,Huang, X.,Zhang, X.,Zhang, M.,Hao, Y.,Guo, H.,Liu, L.N.,Yu, F.,Zhang, P.
Molecular mechanism underlying transport and allosteric inhibition of bicarbonate transporter SbtA.
Proc.Natl.Acad.Sci.USA, 118:-, 2021

PubMed Abstract: SbtA is a high-affinity, sodium-dependent bicarbonate transporter found in the cyanobacterial CO-concentrating mechanism (CCM). SbtA forms a complex with SbtB, while SbtB allosterically regulates the transport activity of SbtA by binding with adenyl nucleotides. The underlying mechanism of transport and regulation of SbtA is largely unknown. In this study, we report the three-dimensional structures of the cyanobacterial sp. PCC 6803 SbtA-SbtB complex in both the presence and absence of HCO and/or AMP at 2.7 Å and 3.2 Å resolution. An analysis of the inward-facing state of the SbtA structure reveals the HCO/Na binding site, providing evidence for the functional unit as a trimer. A structural comparison found that SbtA adopts an elevator mechanism for bicarbonate transport. A structure-based analysis revealed that the allosteric inhibition of SbtA by SbtB occurs mainly through the T-loop of SbtB, which binds to both the core domain and the scaffold domain of SbtA and locks it in an inward-facing state. T-loop conformation is stabilized by the AMP molecules binding at the SbtB trimer interfaces and may be adjusted by other adenyl nucleotides. The unique regulatory mechanism of SbtA by SbtB makes it important to study inorganic carbon uptake systems in CCM, which can be used to modify photosynthesis in crops.

PubMed: 34031249
DOI: 10.1073/pnas.2101632118

実験手法

X-RAY DIFFRACTION (3.2 Å)