Description
A previous study looking at the effect of boron on iron uptake genes in Marinobacter algicola DG 893 gave rise to two groups of such genes based on the effect of boron on their transcription levels. Group 1 genes were upregulated in the presence of boron and have been hypothesized to be affected through the interaction of this element with a global regulatory protein known as Fur. Fur acts as a negative transcriptional repressor by binding to a region of DNA called the fur box when in the presence of high iron. When the Fe-fur protein complex binds to the "fur-box" sequence the transcription of many iron uptake genes is repressed. A further understanding of how boron interacts with the Fur protein requires the development of recombinant protein. Here we will describe the cloning, isolation, purification, and metal binding studies of the recombinant Fur protein obtained from the Gram negative marine bacterium Marinobacter algicola DG893. Group 2 gene/proteins are represented by the ferric binding protein A (FbpA). The transcription and expression levels of the fbpA gene and FbpA protein were downregulated in the presence of high boron concentrations. Since FbpA from M. algicola does not contain a Fur box sequence and is down rather than up regulated by boron, its regulation must involve a different mechanism. In order to further study this effect recombinant protein again had to be developed. Here we will describe the isolation, purification, boron binding and iron binding studies of the recombinant FbpA protein from Marinobacter algicola DG893. The findings from these studies strengthen the link between iron uptake and boron with wide biogeochemical consequences considering that iron limits microorganisms in large areas of the oceans.
