6ki1

The transmembrane domain of a cyanobacterium bicarbonate transporter BicA

spinqualitylabelsall models 6ki1, resolution 2.81Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 6ki1 is a 2 chain structure with sequence from Synechocystis sp. PCC 6803. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.809Å Ligands: BCT, NA, OLC Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function BICA_SYNY3 Low affinity, high-flux Na(+)-dependent bicarbonate transporter (PubMed:31712753). Involved in carbone dioxide-concentrating mechanisms (CCMs) that accumulate CO(2) and improve photosynthetic carbon fixation (PubMed:31712753). Publication Abstract from PubMed Bicarbonate transporters play essential roles in pH homeostasis in mammals and photosynthesis in aquatic photoautotrophs. A number of bicarbonate transporters have been characterized, among which is BicA-a low-affinity, high-flux SLC26-family bicarbonate transporter involved in cyanobacterial CO2-concentrating mechanisms (CCMs) that accumulate CO2 and improve photosynthetic carbon fixation. Here, we report the three-dimensional structure of BicA from Synechocystis sp. PCC6803. Crystal structures of the transmembrane domain (BicA(TM)) and the cytoplasmic STAS domain (BicA(STAS)) of BicA were solved. BicA(TM) was captured in an inward-facing HCO3(-)-bound conformation and adopts a '7+7' fold monomer. HCO3(-) binds to a cytoplasm-facing hydrophilic pocket within the membrane. BicA(STAS) is assembled as a compact homodimer structure and is required for the dimerization of BicA. The dimeric structure of BicA was further analysed using cryo-electron microscopy and physiological analysis of the full-length BicA, and may represent the physiological unit of SLC26-family transporters. Comparing the BicA(TM) structure with the outward-facing transmembrane domain structures of other bicarbonate transporters suggests an elevator transport mechanism that is applicable to the SLC26/4 family of sodium-dependent bicarbonate transporters. This study advances our knowledge of the structures and functions of cyanobacterial bicarbonate transporters, and will inform strategies for bioengineering functional BicA in heterologous organisms to increase assimilation of CO2. Structural mechanism of the active bicarbonate transporter from cyanobacteria.,Wang C, Sun B, Zhang X, Huang X, Zhang M, Guo H, Chen X, Huang F, Chen T, Mi H, Yu F, Liu LN, Zhang P Nat Plants. 2019 Nov;5(11):1184-1193. doi: 10.1038/s41477-019-0538-1. Epub 2019, Nov 11. PMID:31712753 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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