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The sodium‐dependent d ‐glucose transport protein of Helicobacter pylori
Author(s) -
Psakis Georgios,
Saidijam Massoud,
Shibayama Keigo,
Polaczek Julia,
Bettaney Kim E.,
Baldwin Jocelyn M.,
Baldwin Stephen A.,
Hope Ryan,
Essen LarsOliver,
Essenberg Richard C.,
Henderson Peter J. F.
Publication year - 2009
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.2008.06535.x
Subject(s) - biochemistry , biology , glucose transporter , glucokinase , mannose , snf3 , phlorizin , galactose , pep group translocation , hexose , escherichia coli , major facilitator superfamily , phosphoenolpyruvate carboxykinase , enzyme , transporter , gene , endocrinology , saccharomyces cerevisiae , insulin
Summary Helicobacter pylori is a Gram‐negative pathogenic microaerophile with a particular tropism for the mucosal surface of the gastric epithelium. Despite its obligatory microaerophilic character, it can metabolize d ‐glucose and/or d ‐galactose in both oxidative and fermentative pathways via a Na + ‐dependent secondary active transport, a glucokinase and enzymes of the pentose phosphate pathway. We have assigned the Na + ‐dependent transport of glucose to the protein product of the H. pylori 1174 gene. The gene was heterologously expressed in a glucose transport‐deficient Escherichia coli strain, where transport activities of radiolabelled d ‐glucose, d ‐galactose and 2‐deoxy‐ d ‐glucose were restored, consistent with the expected specificity of the hexose uptake system in H. pylori . d ‐Mannose was also identified as a substrate. The HP1174 transport protein was purified and reconstituted into proteoliposomes, where sodium dependence of sugar transport activity was demonstrated. Additionally the tryptophan/tyrosine fluorescence of the purified protein showed quenching by 2‐deoxy‐ d ‐glucose, d ‐mannose, d ‐glucose or d ‐galactose in the presence of sodium ions. This is the first reported purification and characterization of an active glucose transport protein member of the TC 2.1.7 subgroup of the Major Facilitator Superfamily, constituting the route for entry of sugar nutrients into H. pylori . A model is derived of its three‐dimensional structure as a paradigm of the family.