Mercury(II) metallation of Pseudomonas aeruginosa azurin has been characterized structurally and biochemically. The X-ray crystal structure at 1.5 Å of mercury(II) metallated azurin confirms the coordination of mercury at the copper binding active site and a second surface site. These findings are further validated by NMR, Matrix-assisted laser desorption/ionization spectrometry (MALDI), and UV-visible spectroscopic methods indicating copper displacement from the wild-type protein. Bioinformatic analysis has identified homologous human protein domains computationally, and compared them to the structure of azurin, providing a model for human mercury interactions. Study of the mercury-azurin adduct, in combination with other known examples of protein-heavy metal interactions, could provide further insight into the chemical mechanisms of toxicological interactions, leading toward a global understanding of the biological speciation of toxic heavy metals.
Bibliographical noteFunding Information:
We thank the National Science Foundation for the funding to purchase the Bruker Apex II Duo CCD X-ray diffractometer ( CHE-0840446 ). We thank the Kresge Foundation and donors to the Kresge Challenge Program at The University of Akron for the funding used to purchase the 750-Mhz NMR spectrometer. We wish to thank the Leeper group, University of Akron, for their continued assistance, especially Stephanie M. Bilinovich for assisting with NMR. Finally, we thank John H. Richards, California Institute of Technology, and Yi Lu of the University of Illinois at Urbana-Champaign for the gift of the azurin gene.
- X-ray structure