Thermodynamic evidence for conformational coupling between the B and C domains of the mannitol transporter of escherichia coli, enzyme IImtl.

The Journal of Biological Chemistry
W MeijbergG T Robillard

Abstract

The transport across the cytoplasmic membrane and concomitant phosphorylation of mannitol in Escherichia coli is catalyzed by the mannitol-specific transport protein from the phosphoenolpyruvate-dependent phosphotransferase system, enzyme IImtl. Interactions between the cytoplasmic B and the membrane embedded C domain play an important role in the catalytic cycle of this enzyme, but the nature of this interaction is largely unknown. We have studied the thermodynamics of binding of (i) mannitol to enzyme IImtl, (ii) the substrate analog perseitol to enzyme IImtl, (iii) perseitol to phosphorylated enzyme IImtl, and (iv) mannitol to enzyme IImtl treated with trypsin to eliminate the cytoplasmic domains. Analysis of the heat capacity increment of these reactions showed that approximately 50-60 residues are involved in the binding of mannitol and perseitol, but far less in the phosphorylated state or after removal of the B domain. A model is proposed in which binding of mannitol leads to the formation of a contact interface between the two domains, either by folding of unstructured parts or by docking of preexisting surfaces, thus positioning the incoming mannitol close to the phosphorylation site on the B domain to facilitate the t...Continue Reading

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Citations

Dec 13, 2006·Microbiology and Molecular Biology Reviews : MMBR·Josef DeutscherPieter W Postma
Jul 11, 2006·Protein Science : a Publication of the Protein Society·Gertjan VeldhuisBert Poolman
Mar 25, 2014·Biochimica Et Biophysica Acta·Jason G McCoyMing Zhou
Oct 2, 2001·The Journal of Biological Chemistry·Q ChenO Amster-Choder
Mar 30, 2001·The Journal of Biological Chemistry·B A van MontfortG T Robillard

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