The Histidine-binding Protein J Is a Component of Histidine Transport

Abstract

Abstract The histidine-binding protein J, previously shown to be involved in histidine transport in Salmonella typhimurium (Ames, G. F., and Lever, J. (1970) Proc. Nat. Acad. Sci. U. S. A. 66, 1096), is shown unequivocally to be the product of the hisJ gene. A hisJ mutant with an altered J protein and a correspondingly altered histidine transport has been isolated and characterized. The J protein from this strain has an increased temperature sensitivity, besides having altered chromatographic and electrophoretic mobilities. The in vivo effect of the altered J protein is expressed as an increased temperature sensitivity of histidine transport. Our data indicate that the hisJ gene is the structural gene for the J protein and that the J protein is an obligatory component of histidine transport. As expected, there is an excellent correlation between the specificity of transport in the wild type strain and the specificity of binding of the wild type J protein for a variety of amino acids, amino acid analogues, and inhibitors.