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The overproduction of the metalloregulatory protein ArsR in Escherichia coli resulted in elevated levels of arsenite bioaccumulation but also severe reduction in cell growth. These results open up the possibility of using cells overexpressing ArsR as an inexpensive, high-affinity ligand for arsenic removal from contaminated drinking and ground water.

Research has been conducted on metalloregulatory protein MerR exhibiting selectivity toward mercury. The authors describe a method developed for mercury removal via generating microbial biosorbents with surface-exposed MerR.

The metalloregulatory protein MerR, which exhibits high affinity and selectivity toward mercury, was exploited for the construction of microbial biosorbents specific for mercury removal. Whole-cell sorbents were constructed with MerR genetically engineered onto the surface of Escherichia coli cells by using an ice nucleation protein anchor. The presence of surface-exposed MerR on the engineered strains enabled sixfold-higher Hg[sup 2+] biosorption than that found in the wild-type JM109 cells. Hg[sup 2+] binding via MerR was very specific, with no observable decline even in the presence of 100-fold excess Cd[sup 2+] and Zn[sup 2+]. The Hg[sup 2+] binding property of the whole-cell sorbents was also insensitive to different ionic strengths, pHs, and the presence of metal chelators. Since metalloregulatory proteins are currently available for a wide variety of toxic heavy metals, our results suggest that microbial biosorbents overexpressing metalloregulatory proteins may be used similarly for the cleanup of other important heavy metals. [ABSTRACT FROM AUTHOR]

This report describes a new plasmid DNA purification method, which takes advantage of the DNA-binding affinity and specificity of the bacterial metalloregulatory protein MerR, and of the temperature responsiveness of elastin-like proteins (ELPs). Upon increasing the temperature, ELP undergoes a reversible phase transition from water-soluble forms into aggregates, and this property was exploited for the precipitation of plasmid DNA containing the MerR recognition sequence by a simple temperature trigger. In one purification step, plasmid DNA was purified from E. coli cell lysates to a better purity than that prepared by a standard alkaline purification method, with no contaminating chromosomal DNA and cellular proteins. This protein-based approach, in combination with the reversible phase transition feature of ELP, makes the outlined method a promising candidate for large-scale purification of plasmid DNA for sensitive applications such as nonviral gene therapy or DNA vaccines., (Copyright 2004 Wiley Periodicals, Inc.)