2023 Fiscal Year Research-status Report
Acquisition of TrkG added new functionalities to the K+ uptake system of Escherichia coli
| Project/Area Number |
23K13862
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| Research Institution | Tohoku University |
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Principal Investigator |
ELLEN 東北大学, 工学研究科, 特任助教 (40870176)
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| Project Period (FY) |
2023-04-01 – 2025-03-31
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| Keywords | K+ transporter / membrane protein / potassium ion |
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| Outline of Annual Research Achievements |
K+ is an essential cation that has many important functions for living cells. Cells tend to accumulate high intracellular concentrations of K+ via protein transporters located in the cell membrane. The Trk/Ktr/HKT K+ transporter family is one of the main K+ transporters found in non-animal cells, including bacteria, yeast,and plants. In the model organism, Escherichia coli K-12, Trk transporter is further divided into two types: TrkG and TrkH. Although they are homologous protein, previously, we had found the differences in their uptake activities. But the information about their gene regulation is very limited. In this study, we investigate the expression of trkG and trkH in relation to various factors, such as salt stress, extracellular K+ concentration and xenogenic silencing proteins.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
Factors affecting gene expression regulation of trkG and TrkH in Escherichia coli K-12 were examined. Since TrkG activity is closely linked to Na+, the impact of salt (NaCl) stress on its expression was investigated. Interestingly, trkG expression remained unaffected by NaCl stress. In addition, the expression of trkG and trkH was also independent of K+ concentrations in the external enviornment, suggesting they most likely to be expressed consitutively. The most notable differences between trkG and trkH expression is in the involvment of the xenogenic silencing proteins. trkG expression significantly increased in their absence (using knock-out mutant) compared to unchanged trkH. However, trkG expression persists in the wild-type, suggesting incomplete silencing of trkG by those proteins.
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| Strategy for Future Research Activity |
In our forthcoming research, I aim to elucidate the role of TrkG in the K+ uptake system of E. coli K-12. Despite E. coli's efficiency, the retention of both Trk transporters remains puzzling. Utilizing knock-out mutants, I will assess various stress conditions to pinpoint when trkG activity becomes vital for E. coli growth. Additionally, I plan to employ my own E. coli K+ transporter deficient mutants to identify functional K+ transporters in the plant model organism, Arabidopsis thaliana. Potassium is crucial for growth, reproduction, and productivity, and the discovery of new plant K+ transporters using our library of A. thaliana membrane proteins will significantly enhance our understanding of plant nutrient uptake and stress responses.
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| Causes of Carryover |
I could save up some reagents and article costs. I will the budget next fiscal year for going to international conference to present my result
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