bi9631632_si_001.pdf (291.72 kB)
Structures of the Reduced and Mercury-Bound Forms of MerP, the Periplasmic Protein from the Bacterial Mercury Detoxification System†,‡
journal contribution
posted on 1997-06-10, 00:00 authored by Ruth A. Steele, Stanley J. OpellaBacteria carrying plasmids with the mer
operon, which encodes the proteins responsible for
the bacterial mercury detoxification system, have the ability to
transport Hg(II) across the cell membrane
into the cytoplasm where it is reduced to Hg(0). This is
significant because metallic mercury is relatively
nontoxic and volatile and thus can be passively eliminated. The
structures of the reduced and mercury-bound forms of merP, the periplasmic protein, which binds Hg(II)
and transfers it to the membrane transport
protein merT, have been determined in aqueous solution by
multidimensional NMR spectroscopy. The
72-residue merP protein has a βαββαβ fold with the two α
helices overlaying a four-strand antiparallel
β sheet. Structural differences between the reduced and
mercury-bound forms of merP are localized to
the metal binding loop containing the consensus sequence GMTCXXC.
The structure of the mercury-bound form of merP shows that Hg(II) is bicoordinate with the Cys
side chain ligands, and this is confirmed
by the chemical shift frequency of the 199Hg
resonance.