Open AccessBacterial mercury resistance from atoms to ecosystems
Author(s) -
Barkay Tamar,
Miller Susan M,
Summers Anne O
Publication year - 2003
Publication title -
fems microbiology reviews
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.91
H-Index - 212
eISSN - 1574-6976
pISSN - 0168-6445
DOI - 10.1016/s0168-6445(03)00046-9
Subject(s) - operon , biology , bacteria , transposable element , plasmid , microbiology and biotechnology , mercury (programming language) , efflux , genetics , gene , periplasmic space , biochemistry , escherichia coli , genome , computer science , programming language
Bacterial resistance to inorganic and organic mercury compounds (HgR) is one of the most widely observed phenotypes in eubacteria. Loci conferring HgR in Gram‐positive or Gram‐negative bacteria typically have at minimum a mercuric reductase enzyme (MerA) that reduces reactive ionic Hg(II) to volatile, relatively inert, monoatomic Hg(0) vapor and a membrane‐bound protein (MerT) for uptake of Hg(II) arranged in an operon under control of MerR, a novel metal‐responsive regulator. Many HgR loci encode an additional enzyme, MerB, that degrades organomercurials by protonolysis, and one or more additional proteins apparently involved in transport. Genes conferring HgR occur on chromosomes, plasmids, and transposons and their operon arrangements can be quite diverse, frequently involving duplications of the above noted structural genes, several of which are modular themselves. How this very mobile and plastic suite of proteins protects host cells from this pervasive toxic metal, what roles it has in the biogeochemical cycling of Hg, and how it has been employed in ameliorating environmental contamination are the subjects of this review.