Both Lobes of the Soluble Receptor of the Periplasmic Histidine Permease, an ABC Transporter (Traffic ATPase), Interact with the Membrane-bound Complex: EFFECT OF DIFFERENT LIGANDS AND CONSEQUENCES FOR THE MECHANISM OF ACTION

Cheng E Liu,Pei-Qi Liu,Amnon Wolf,Erick Lin,Giovanna Ferro-Luzzi Ames

doi:10.1074/jbc.274.2.739

Cheng E Liu, Pei-Qi Liu + Show 3 more

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https://doi.org/10.1074/jbc.274.2.739

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Abstract

The histidine permease of Salmonella typhimurium is an ABC transporter (traffic ATPase). The liganded soluble receptor, the histidine-binding protein HisJ, interacts with the membrane-bound complex HisQMP2 and stimulates its ATPase activity, which results in histidine translocation. In this study, we utilized HisJ proteins with mutations in either of the two lobes and wild type HisJ liganded with different substrates to show that each lobe carries an interaction site and that both lobes are involved in inducing (stimulating) the ATPase activity. We suggest that the spatial relationship between the lobes is one of the factors recognized by the membrane-bound complex in dictating the efficiency of the induction signal and of translocation. Several of the key residues involved have been identified. In addition, using constitutive ATPase mutants, we show that the binding protein provides some additional essential function(s) in translocation that is independent of the stimulation of ATP hydrolysis, and one possible mechanism is proposed, which includes the notion that liganded HisJ has different optimal conformations for signaling and for translocation.

Highlights

The histidine permease of Salmonella typhimurium is an ABC transporter
We utilized HisJ proteins with mutations in either of the two lobes and wild type HisJ liganded with different substrates to show that each lobe carries an interaction site and that both lobes are involved in inducing the ATPase activity
We suggest that the spatial relationship between the lobes is one of the factors recognized by the membranebound complex in dictating the efficiency of the induction signal and of translocation

Summary

Introduction

The histidine permease of Salmonella typhimurium is an ABC transporter (traffic ATPase). The liganded soluble receptor, the histidine-binding protein HisJ, interacts with the membrane-bound complex HisQMP2 and stimulates its ATPase activity, which results in histidine translocation. We utilized HisJ proteins with mutations in either of the two lobes and wild type HisJ liganded with different substrates to show that each lobe carries an interaction site and that both lobes are involved in inducing (stimulating) the ATPase activity. We utilized HisJ proteins mutated in either of the two lobes and wild type HisJ liganded with different substrates to show, using biochemical tools, that each HisJ lobe carries an interaction site, that both lobes are involved in inducing the ATPase activity, and, that the spatial relationship between the lobes may be one of the factors dictating the efficiency of the induction signal and of translocation. Evidence is provided that the soluble receptor supplies some essential function(s) in translocation that is independent of the stimulation of ATP hydrolysis, because translocation is very poor when ATP hydrolysis is constitutively and maximally expressed, unless HisJ is present

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