Characterisation of cyanobacterial bicarbonate transporters in E. coli shows that SbtA homologs are functional in this heterologous expression system
| Autor: | Susan M. Howitt, Loraine Rourke, Britta Förster, Jiahui Du, G. Dean Price |
|---|---|
| Rok vydání: | 2014 |
| Předmět: |
Cyanobacteria
Chloroplasts Bicarbonate Cell Membranes lcsh:Medicine Plant Science medicine.disease_cause Biochemistry Microbiology chemistry.chemical_compound Bacterial Proteins Microbial Physiology medicine Escherichia coli Bacterial Physiology Photosynthesis lcsh:Science Synechococcus Multidisciplinary biology Plant Biochemistry lcsh:R Synechocystis Biology and Life Sciences Membrane Proteins Transporter Biological Transport Bacteriology Cell Biology biology.organism_classification Chloroplast Transmembrane Proteins Bicarbonates Metabolism chemistry lcsh:Q Plant Biotechnology Heterologous expression Cellular Structures and Organelles Carrier Proteins Research Article Biotechnology |
| Zdroj: | PLoS ONE PLoS ONE, Vol 9, Iss 12, p e115905 (2014) |
| ISSN: | 1932-6203 |
| Popis: | Cyanobacterial HCO3(-) transporters BCT1, SbtA and BicA are important components of cyanobacterial CO2-concentration mechanisms. They also show potential in applications aimed at improving photosynthetic rates and yield when expressed in the chloroplasts of C3 crop species. The present study investigated the feasibility of using Escherichia coli to assess function of a range of SbtA and BicA transporters in a heterologous expression system, ultimately for selection of transporters suitable for chloroplast expression. Here, we demonstrate that six β-forms of SbtA are active in E. coli, although other tested bicarbonate transporters were inactive. The sbtA clones were derived from Synechococcus sp. WH5701, Cyanobium sp. PCC7001, Cyanobium sp. PCC6307, Synechococcus elongatus PCC7942, Synechocystis sp. PCC6803, and Synechococcus sp. PCC7002. The six SbtA homologs varied in bicarbonate uptake kinetics and sodium requirements in E. coli. In particular, SbtA from PCC7001 showed the lowest uptake affinity and highest flux rate and was capable of increasing the internal inorganic carbon pool by more than 8 mM relative to controls lacking transporters. Importantly, we were able to show that the SbtB protein (encoded by a companion gene near sbtA) binds to SbtA and suppresses bicarbonate uptake function of SbtA in E. coli, suggesting a role in post-translational regulation of SbtA, possibly as an inhibitor in the dark. This study established E. coli as a heterologous expression and analysis system for HCO3(-) transporters from cyanobacteria, and identified several SbtA transporters as useful for expression in the chloroplast inner envelope membranes of higher plants. |
| Databáze: | OpenAIRE |
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