title: MerF is a mercury transport protein: different structures but a common mechanism for mercuric ion transporters?
abstract: Mercury resistance determinants are widespread in Gram-negative bacteria, but vary in the number and identity of genes present. We have shown that the merF gene from plasmid pMER327/419 encodes a 8.7 kDa mercury transport protein, by determining in vivo mercury volatilisation when MerF is expressed in the presence of mercuric reductase. We have confirmed that MerC of Tn21 is also a mercuric ion transporter. We have been able to detect interaction of the periplasmic protein MerP only with the MerT transporter, and not with MerF or MerC. Hydropathy analysis led to the prediction of models for MerT, MerC and MerF having three, four and two transmembrane regions respectively. In all three cases one pair of cysteine residues is predicted to be within the inner membrane with a second pair of cysteine residues on the cytoplasmic face, and the second helix contains a proline and at least one charged residue. The mechanisms of mercuric ion transport may be similar in these transporters even though their structures in the membrane differ.
authors.affiliation: School of Biosciences, The University of Birmingham, Edgbaston, Birmingham, UK.
authors.forename: J R
authors.initials: JR
authors.lastname: Wilson
authors.forename: C
authors.initials: C
authors.lastname: Leang
authors.forename: A P
authors.initials: AP
authors.lastname: Morby
authors.forename: J L
authors.initials: JL
authors.lastname: Hobman
authors.forename: N L
authors.initials: NL
authors.lastname: Brown
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins; D002352:Carrier Proteins / Q000737:chemistry* / Q000378:metabolism; D027682:Cation Transport Proteins; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000737:chemistry* / Q000378:metabolism; D017136:Ion Transport; D008565:Membrane Proteins / Q000737:chemistry* / Q000378:metabolism; D008628:Mercury / Q000378:metabolism*; D008954:Models, Biological; D008969:Molecular Sequence Data; D010957:Plasmids
chemical_list: D001426:Bacterial Proteins; D002352:Carrier Proteins; D027682:Cation Transport Proteins; D008565:Membrane Proteins; C408446:MerF mercury transport protein, Pseudomonas fluorescens; C094115:mercury transport protein, bacterial; C072715:merC protein, Acidithiobacillus ferrooxidans; D008628:Mercury