Extreme Zinc-Binding Thermodynamics of the Metal Sensor/Regulator Protein, ZntR

Hitomi, Yutaka; Outten, Caryn E.; O’Halloran, Thomas V.

doi:10.1021/ja016146v

Cited by 86 publications

(91 citation statements)

References 27 publications

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“…A control experiment was done to test the effect of the membraneimpermeable divalent cation chelator Na 2 EDTA and membrane-permeable zinc-specific chelator TPEN (Hitomi et al, 2001) …”

Section: Effect Of Zinc Chelators On Si Uptakementioning

confidence: 99%

Silicon Uptake in Diatoms Revisited: A Model for Saturable and Nonsaturable Uptake Kinetics and the Role of Silicon Transporters

2007

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The silicic acid uptake kinetics of diatoms were studied to provide a mechanistic explanation for previous work demonstrating both nonsaturable and Michaelis-Menten-type saturable uptake. Using 68 Ge(OH) 4 as a radiotracer for Si(OH) 4 , we showed a time-dependent transition from nonsaturable to saturable uptake kinetics in multiple diatom species. In cells grown under silicon (Si)-replete conditions, Si(OH) 4 uptake was initially nonsaturable but became saturable over time. Cells prestarved for Si for 24 h exhibited immediate saturable kinetics. Data suggest nonsaturability was due to surge uptake when intracellular Si pool capacity was high, and saturability occurred when equilibrium was achieved between pool capacity and cell wall silica incorporation. In Thalassiosira pseudonana at low Si(OH) 4 concentrations, uptake followed sigmoidal kinetics, indicating regulation by an allosteric mechanism. Competition of Si(OH) 4 uptake with Ge(OH) 4 suggested uptake at low Si(OH) 4 concentrations was mediated by Si transporters. At high Si(OH) 4 , competition experiments and nonsaturability indicated uptake was not carrier mediated and occurred by diffusion. Zinc did not appear to be directly involved in Si(OH) 4 uptake, in contrast to a previous suggestion. A model for Si(OH) 4 uptake in diatoms is presented that proposes two control mechanisms: active transport by Si transporters at low Si(OH) 4 and diffusional transport controlled by the capacity of intracellular pools in relation to cell wall silica incorporation at high Si(OH) 4 . The model integrates kinetic and equilibrium components of diatom Si(OH) 4 uptake and consistently explains results in this and previous investigations.

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“…A control experiment was done to test the effect of the membraneimpermeable divalent cation chelator Na 2 EDTA and membrane-permeable zinc-specific chelator TPEN (Hitomi et al, 2001) …”

Section: Effect Of Zinc Chelators On Si Uptakementioning

confidence: 99%

Silicon Uptake in Diatoms Revisited: A Model for Saturable and Nonsaturable Uptake Kinetics and the Role of Silicon Transporters

2007

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“…This challenge is especially imposing for metal sensing (1)(2)(3)(4)(5), because many metal ions are very similar and sometimes even identical in charge, ionic radius, and other properties, making them difficult to detect at ultra-low concentrations with no interference by other metal ions. Meeting such a challenge is critical in advancing a number of fields including chemistry, biology, environmental engineering, and medicine.…”

mentioning

confidence: 99%

A catalytic beacon sensor for uranium with parts-per-trillion sensitivity and millionfold selectivity

Liu

Brown

Meng

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

488

476

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Here, we report a catalytic beacon sensor for uranyl (UO 2 2؉ ) based on an in vitro-selected UO 2 2؉ -specific DNAzyme. The sensor consists of a DNA enzyme strand with a 3 quencher and a DNA substrate with a ribonucleotide adenosine (rA) in the middle and a fluorophore and a quencher at the 5 and 3 ends, respectively. The presence of UO 2 2؉ causes catalytic cleavage of the DNA substrate strand at the rA position and release of the fluorophore and thus dramatic increase of fluorescence intensity. The sensor has a detection limit of 11 parts per trillion (45 pM), a dynamic range up to 400 nM, and selectivity of >1-million-fold over other metal ions. The most interfering metal ion, Th(IV), interacts with the fluorescein fluorophore, causing slightly enhanced fluorescence intensity, with an apparent dissociation constant of Ϸ230 M. This sensor rivals the most sensitive analytical instruments for uranium detection, and its application in detecting uranium in contaminated soil samples is also demonstrated. This work shows that simple, cost-effective, and portable metal sensors can be obtained with similar sensitivity and selectivity as much more expensive and sophisticated analytical instruments. Such a sensor will play an important role in environmental remediation of radionuclides such as uranium.DNA ͉ DNAzyme ͉ fluorescence ͉ deoxyribozyme ͉ catalytic DNA

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“…8,9) Moreover, zinc is essential for regulating DNA synthesis and mitosis, thereby inhibiting apoptosis. [10][11][12][13] Zinc supplementation at 30 mM has inhibited ethanol-induced apoptosis of immune cells, 14) and also of liver cancer HepG2 cells with increased cellular levels of GSH. 15) On the other hand, zinc is associated with growth retardation and neurological disorders.…”

mentioning

confidence: 99%

Effects of Exogenous Zinc on the Cellular Zinc Distribution and Cell Cycle of A549 Cells

Yuan

Wang

et al. 2012

Bioscience, Biotechnology, and Biochemistry

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Extreme Zinc-Binding Thermodynamics of the Metal Sensor/Regulator Protein, ZntR

Cited by 86 publications

References 27 publications

Silicon Uptake in Diatoms Revisited: A Model for Saturable and Nonsaturable Uptake Kinetics and the Role of Silicon Transporters

Silicon Uptake in Diatoms Revisited: A Model for Saturable and Nonsaturable Uptake Kinetics and the Role of Silicon Transporters

A catalytic beacon sensor for uranium with parts-per-trillion sensitivity and millionfold selectivity

Effects of Exogenous Zinc on the Cellular Zinc Distribution and Cell Cycle of A549 Cells

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