Membrane topology of the cyanobacterial bicarbonate transporter, BicA, a member of the SulP (SLC26A) family
| Autor: | Megan C. Shelden, Susan M. Howitt, G. D. Price |
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| Rok vydání: | 2009 |
| Předmět: |
Models
Molecular Synechococcus Sequence Homology Amino Acid biology Two-hybrid screening Amino Acid Motifs Anion Transport Proteins Bicarbonate transporter protein Cell Biology Computational biology Carbon Dioxide biology.organism_classification Peptide Mapping Transmembrane protein Protein Structure Tertiary Transport protein Bacterial Proteins Biochemistry Membrane topology Humans Eukaryote Molecular Biology Function (biology) |
| Zdroj: | Molecular Membrane Biology. 27:12-22 |
| ISSN: | 1464-5203 0968-7688 |
| Popis: | We have completed the first comprehensive transmembrane topology determination for a member of the ubiquitous and important SulP/SLC26 family of coupled anion transporters found in eukaryotes and prokaryotes. The prokaryotic member that we have mapped, namely BicA from Synechococcus PCC7002, is an important Na(+)-dependent bicarbonate transporter that is likely to play a major role in global primary productivity via the CO(2) concentrating mechanism in cyanobacteria. We experimentally determined the topology based on phoA-lacZ topology mapping combined with reference to a range of predictive models based on hydropathy analysis and positive charge distribution. The 12-TMH structure for BicA is characterized by tight turns between several pairs of TMH and it features a prominent cytoplasmically-located STAS domain that is characteristic of the SulP family. A key difference from previous predicted models is that we identify a cytoplasmic loop between helices 8 and 9 where previous models suggested a TMH. This region includes a highly conserved motif that defines the SulP family. The identification of this region as cytoplasmic, rather than transmembrane, has implications for the function and perhaps regulation of SulP family members. This finding is used to reinterpret mutagenesis data relating to highly conserved residues in this region from both plant and human SulP transporters. |
| Databáze: | OpenAIRE |
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