A single amino acid substitution in a histidine-transport protein drastically alters its mobility in sodium dodecyl sulfate-polyacrylamide gel electrophoresis.
Mutation hisJ5625 has altered the histidine-binding protein J of Salmonella typhimurium such that histidine transport is impaired, even though binding of histidine by the J protein is unimpaired [Kustu, S.G., & Ames, G.F. (1974) J. Biol. Chem. 249, 6976--6983]. We have determined by protein analytical methods that the only effect of this mutation has been the substitution of a cysteine residue for an arginine at a site in the interior of the polypeptide chain. This arginine residue is therefore potentially essential for the transport function of the protein. The mutant protein migrates in sodium dodecyl sulfate-polyacrylamide gel electrophoresis more slowly than the wild type protein, as if its molecular weight were greater by as much as 2000. Since this behavior is apparently due to a single amino acid replacement, a molecular weight difference even between two closely related proteins should not be inferred solely on the basis of sodium dodecyl sulfate gel electrophoresis.
D000596:Amino Acids / Q000032:analysis; D001692:Biological Transport; D002352:Carrier Proteins / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D006639:Histidine / Q000378:metabolism*; D009154:Mutation; D010446:Peptide Fragments / Q000032:analysis; D033902:Periplasmic Binding Proteins; D012486:Salmonella typhimurium / Q000378:metabolism; D012967:Sodium Dodecyl Sulfate; D014357:Trypsin
D000596:Amino Acids; D002352:Carrier Proteins; D010446:Peptide Fragments; D033902:Periplasmic Binding Proteins; C018963:histidine-binding protein; D012967:Sodium Dodecyl Sulfate; D006639:Histidine; D014357:Trypsin