Understanding the toxic effects of mercury and its cycling in the environment requires detailed characterization of its interaction with proteins. Computational approaches are ideally suited to studies of mercury in proteins because they provide a detailed picture and circumvent issues associated with toxicity. This work highlights eight years of combined computational and experimental studies on proteins and enzymes involved in mercury methylation, demethylation, and reduction.
This work has greatly expanded the molecular understanding of biological transformations of mercury. Additionally, this work on mercury in proteins is placed in the context of what is required for comprehensive multi-scale modeling of environmental mercury cycling.
Mercury is a naturally occurring element released into the biosphere both by natural processes and anthropogenic activities. Its reduced, elemental form Hg(0) is relatively nontoxic. But, other forms such as Hg2+ and, in particular, its methylated form, methylmercury, are toxic with deleterious effects on both ecosystems and humans. Microorganisms play important roles in the transformation of mercury in the environment. Inorganic Hg2+ can be methylated by certain bacteria and archaea to form methylmercury. Conversely, bacteria also demethylate methylmercury and reduce Hg2+ to relatively inert Hg(0). Transformations and toxicity occur as a result of mercury interacting with various proteins. Understanding the toxic effects of mercury and its cycling in the environment requires characterization of these interactions. Computational approaches are ideally suited to studies of mercury in proteins because they can provide a detailed picture and circumvent issues associated with toxicity. This work describes computational methods for investigating and characterizing how mercury binds to proteins, how inter- and intra-protein transfer of mercury is orchestrated in biological systems, and how chemical reactions in proteins transform the metal. Also described are quantum chemical analyses of aqueous Hg(II), which reveal critical factors that determine ligand binding propensities. A perspective is provided on how chemical reasoning was used to discover how microorganisms methylate mercury. Combined computational and experimental studies of the proteins and enzymes of the mer operon, a suite of genes that confers mercury resistance in many bacteria, also are highlighted. Lastly, work on mercury in proteins is placed in the context of what is needed for a comprehensive multi-scale model of environmental mercury cycling.
Parks, J.M., and Smith, J.C. In press. "Modeling Mercury in Proteins." In Methods in Enzymology: Computational Approaches for Studying Enzyme Mechanism, edited by Gregory Voth. Elsevier, Inc., 2016.
Security Notice | Contact Eric Pierce, ORNL | Website Questions | Site Map
File last modified: Tuesday, February 04, 2020
The ORNL Mercury SFA is sponsored by the Subsurface Biogeochemical Research (SBR) program within the U.S. Department of Energy's Office of Biological and Environmental Research.