Biochemical characterization of HgCl2-inducible polypeptides encoded by the mer operon of plasmid R100.
Minicells carrying the subcloned mer operon from plasmid R100 were pulse-labeled with [35S]methionine, and the labeled polypeptides were analyzed at various subsequent times by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The Hg(II) reductase monomer encoded by plasmid R100 occurred as two proteins of 69 and 66 kilodaltons (kd). The minor 66-kd protein is a modified form of the 69-kd protein. This modification occurs in vivo. Both of these mer proteins are found in the soluble fraction of the cell; however, the 66-kd protein appears to have a slight affinity for the cellular envelope. Both the 69- and 66-kd mer proteins have pI values greater (pI = 5.8) than that reported (pI = 5.3) for the analogous monomer encoded by plasmid R831. The 15.1- and 14-kd mer proteins are localized in the inner membrane and are probably elements of the mer-determined Hg(II) uptake system. These two mer membrane proteins, which are antigenically unrelated to the Hg(II) reductase monomer, are quite basic (pI values greater than 7.8). The 12-kd mer protein is also a basic polypeptide that is present in the soluble fraction of the cell. Unlike the two membrane-bound mer proteins, the 12-kd mer protein is processed from a 13-kd precursor.
D001426:Bacterial Proteins / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics; D007526:Isoelectric Point; D008565:Membrane Proteins / Q000235:genetics*; D008627:Mercuric Chloride; D008628:Mercury / Q000494:pharmacology*; D008970:Molecular Weight; D009876:Operon; D010088:Oxidoreductases / Q000235:genetics; D011815:R Factors
D001426:Bacterial Proteins; D008565:Membrane Proteins; D008627:Mercuric Chloride; D010088:Oxidoreductases; C021551:mercuric reductase; D008628:Mercury