Femtomolar sensitivity of metalloregulatory proteins controlling zinc homeostasis
Femtomolar sensitivity of metalloregulatory proteins controlling zinc homeostasis
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DOI：
10.1126/science.1060331
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发表时间：
2001-06-29
期刊：
影响因子：
56.9
通讯作者：
O'Halloran, TV
中科院分区：
文献类型：
--
作者：
Outten, CE;O'Halloran, TV
细胞内锌被认为是可利用的游离或松散结合的锌（II）离子在微摩尔至皮摩尔范围内的细胞溶质池。为了测试这一点，我们确定了锌传感器的机制，控制金属的吸收或输出在大肠杆菌和校准他们的响应对化学定义的游离线浓度。而细胞线配额是毫摩尔，游离锌（II）的浓度，触发转录的锌吸收或外排机制是飞摩尔，或六个数量级小于一个原子每个细胞。这是不一致的游离锌（II）的胞质池，并建议一个非凡的细胞内锌结合能力。因此，细胞严格控制胞质金属浓度，即使是相对低毒性的金属，如锌。
Intracellular zinc is thought to be available in a cytosolic pool of free or Loosely bound Zn(II) ions in the micromolar to picomolar range. To test this, we determined the mechanism of zinc sensors that control metal uptake or export in Escherichia coli and calibrated their response against the thermodynamically defined free line concentration. Whereas the cellular line quota is millimolar, free Zn(II) concentrations that trigger transcription of zinc uptake or efflux machinery are femtomolar, or six orders of magnitude Less than one atom per cell. This is not consistent with a cytosolic pool of free Zn(II) and suggests an extraordinary intracellular zinc-binding capacity. Thus, cells exert tight control over cytosolic metal concentrations, even for relatively Low-toxicity metals such as zinc.