Complete nucleotide sequence and identification of membrane components of the histidine transport operon of S. typhimurium

Abstract

The nucleotide sequence of the entire histidine transport operon from Salmonella typhimurium has been determined and is shown to consist of four genes, hisJ, hisQ, hisM and hisP. This operon provides the only example of a binding protein-dependent transport system for which the total number of protein components is known. Determination of the amino acid compositions and sequences of these four transport proteins, together with analysis of various transport mutants, allows us to propose a molecular model for binding protein-dependent transport.

Structure and function of ABC transporters: the ATP switch provides flexible control

“…An understanding of how ABC transporters work to mediate directional transport of substrates across lipid membranes has been a challenge since the first sequence of a complete ABC transporter was obtained nearly 25 years ago [2]. Insights from recent biochemical, structural and genetic studies of several ABC transporters have led to the 'ATP switch' model of function [3].…”

Characterization of the Adenosine Triphosphatase Activity of the Periplasmic Histidine Permease, a Traffic ATPase (ABC Transporter)

“…The existence of such a site in HisQMP 2 has been suggested by the properties of receptor-independent mutants (32,35), the inhibition of in vitro transport by histidine trapped inside PLS (6), and the altered substrate specificity of several strains carrying mutations in either HisQ or HisM (31). The function of this postulated site might be to bind the histidine released from liganded HisJ and initiate a series of conformational changes required for trans- b IC 50 is the concentration which gives 50% inhibition in the presence of 2 mM ATP.…”

“…Effect of Histidine-It has been frequently hypothesized that the membrane-bound complex of periplasmic permeases carries a substrate-binding site (6,(31)(32)(33)(34). The existence of such a site in HisQMP 2 has been suggested by the properties of receptor-independent mutants (32,35), the inhibition of in vitro transport by histidine trapped inside PLS (6), and the altered substrate specificity of several strains carrying mutations in either HisQ or HisM (31).…”

Diversity of transport mechanisms: common structural principles

“…These proteins are part of a transport system that is composed of two identical or homologous cytoplasmic membrane domains and two identical or homologous peripheral membrane-associated ATPbinding domains (Fig. 1a) 2 . In Gramnegative bacteria, SBPs freely diffuse in the periplasm, whereas in Gram-positive bacteria, they are often anchored to the cytoplasmic membrane by a lipid moiety, and some are even fused to the membrane domain 3 .…”