Molecular mechanism underlying transport and allosteric inhibition of bicarbonate transporter SbtA
Sunzhenhe Fang, Xiaowei Huang, Xue Zhang, Minhua Zhang, Yahui Hao, Hui Guo, Lu‐Ning Liu, Fang Yu, Peng Zhang
Abstract
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.