Biomolecular Structure, Dynamics, and Simulation
The objective of this research is to understand biochemical mechanisms involved in bacterial resistance to Hg and in Hg methylation by examining biomolecular conformations and mechanisms relevant for Hg species uptake, transfer, and release. Initial focus will be on the enzymatic mechanism of the organomercurial lyase MerB which is responsible for transformation of methyl mercury to Hg(II). Using the available crystal structure of the MerB enzyme, mixed quantum mechanical/ molecular mechanical simulations will be performed to understand the reaction mechanism by which MerB cleaves Methyl mercury to release Hg(II). The role of the N-terminal domain NmerA in the acquisition and transfer of Hg(II) to the active site for reduction will be elucidated. Research will attempt to resolve the mechanics involved in Hg(II)-dependent transcriptional regulation of genes in the mer operon. The reduction of Hg(II) by dissimilatory reduction processes will be investigated. Out year effort will focus on cloning and overexpression of genes coding for relevant enzymes involved in mercury methylation in close coordination with Microbial Transformations and Genetics studies. The computational investigation will also study demethylation involving organic compounds and will contribute to a better understanding of ligand exchange reactions described in the abiotic study.