A Single Amino Acid Substitution in a Histidine-Transport Protein Drastically Alters its Mobility in Sodium Dodecyl Sulfate-Polyacrylamide Gel Electrophoresis

Document Type

Article

Language

eng

Publication Date

1979

Publisher

American Chemical Society

Source Publication

Biochemistry

Source ISSN

0006-2960

Abstract

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. 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.

Comments

Biochemistry, Vol. 18, No. 19 (1979): 4159-4165. DOI.

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