論文 - 詳細
| RRC ID | 3953 |
|---|---|
| 著者 | Naseem R, Holland IB, Jacq A, Wann KT, Campbell AK. |
| タイトル | pH and monovalent cations regulate cytosolic free Ca(2+) in E. coli. |
| ジャーナル | Biochim Biophys Acta |
| Abstract |
The results here show for the first time that pH and monovalent cations can regulate cytosolic free Ca(2+) in E. coli through Ca(2+) influx and efflux, monitored using aequorin. At pH 7.5 the resting cytosolic free Ca(2+) was 0.2-0.5 microM. In the presence of external Ca(2+) (1 mM) at alkaline pH this rose to 4 microM, being reduced to 0.9 microM at acid pH. Removal of external Ca(2+) caused an immediate decrease in cytosolic free Ca(2+) at 50-100 nM s(-1). Efflux rates were the same at pH 5.5, 7.5 and 9.5. Thus, ChaA, a putative Ca(2+)/H(+)exchanger, appeared not to be a major Ca(2+)-efflux pathway. In the absence of added Na(+), but with 1 mM external Ca(2+), cytosolic free Ca(2+) rose to approximately 10 microM. The addition of Na(+)(half maximum 60 mM) largely blocked this increase and immediately stimulated Ca(2+) efflux. However, this effect was not specific, since K(+) also stimulated efflux. In contrast, an increase in osmotic pressure by addition of sucrose did not significantly stimulate Ca(2+) efflux. The results were consistent with H(+) and monovalent cations competing with Ca(2+) for a non-selective ion influx channel. Ca(2+) entry and efflux in chaA and yrbG knockouts were not significantly different from wild type, confirming that neither ChaA nor YrbG appear to play a major role in regulating cytosolic Ca(2+) in Escherichia coli. The number of Ca(2+) ions calculated to move per cell per second ranged from <1 to 100, depending on conditions. Yet a single eukaryote Ca(2+) channel, conductance 100 pS, should conduct >6 million ions per second. This raises fundamental questions about the nature and regulation of Ca(2+) transport in bacteria, and other small living systems such as mitochondria, requiring a new mathematical approach to describe such ion movements. The results have important significance in the adaptation of E. coli to different ionic environments such as the gut, fresh water and in sea water near sewage effluents. |
| 巻・号 | 1778(6) |
| ページ | 1415-22 |
| 公開日 | 2008-6-1 |
| DOI | 10.1016/j.bbamem.2008.02.006 |
| PII | S0005-2736(08)00075-8 |
| PMID | 18342619 |
| MeSH | Adaptation, Physiological* / genetics Calcium / metabolism* Calcium / pharmacology Cation Transport Proteins / genetics Cation Transport Proteins / metabolism* Cations, Monovalent / metabolism Escherichia coli / genetics Escherichia coli / metabolism* Escherichia coli Proteins / genetics Escherichia coli Proteins / metabolism* Gene Deletion Hydrogen-Ion Concentration Ion Transport / genetics Potassium / metabolism* |
| IF | 3.411 |
| 引用数 | 20 |
| WOS 分野 | BIOPHYSICS BIOCHEMISTRY & MOLECULAR BIOLOGY |
| オルトメトリクス指標 |
オルトメトリクス指標項目
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| 最多言及媒体 | Patent(IFI CLAIMS) |
| 各媒体での言及数の合計 | 2 |
| 過去6か月間でのオルトメトリクス指標の変動値 | 0.0 |
| リソース情報 | |
| 原核生物(大腸菌) | CV-41(JM109) ME9044(MG1655) Keio collection |