Abstract
In this chapter, we summarize recent work from our laboratory and provide new perspective
on two important aspects of bacterial mercury resistance: the molecular mechanism of
transcriptional regulation by MerR, and the enzymatic cleavage of the Hg-C bond in
methylmercury by the organomercurial lyase, MerB. Molecular dynamics (MD) simulations of
MerR reveal an opening-and-closing dynamics, which may be involved in initiating transcription
of mercury resistance genes upon Hg(II) binding. Density functional theory (DFT) calculations
on an active-site model of the enzyme reveal how MerB catalyzes the Hg-C bond cleavage using
cysteine coordination and acid-base chemistry. These studies provide insight into the detailed
mechanisms of microbial gene regulation and defense against mercury toxicity.
