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Iron acquisition and virulence in Helicobacter pylori : a major role for FeoB, a high‐affinity ferrous iron transporter
Author(s) -
Velayudhan Jyoti,
Hughes Nicky J.,
McColm Andrew A.,
Bagshaw Julie,
Clayton Chris L.,
Andrews Simon C.,
Kelly David J.
Publication year - 2000
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 - 10.1046/j.1365-2958.2000.01987.x
Subject(s) - biology , virulence , helicobacter pylori , transporter , ferrous , microbiology and biotechnology , genetics , gene , materials science , metallurgy
The genome sequence of Helicobacter pylori suggests that this bacterium possesses several Fe acquisition systems, including both Fe 2+ ‐ and Fe 3+ ‐citrate transporters. The role of these transporters was investigated by generating insertion mutants in feoB , tonB , fecA1 and fecDE . Fe transport in the feoB mutant was ≈ 10‐fold lower than in the wild type (with 0.5 μM Fe), irrespective of whether Fe was supplied in the Fe 2+ or Fe 3+ form. In contrast, transport rates were unaffected by the other mutations. Complementation of the feoB mutation fully restored both Fe 2+ and Fe 3+ transport. The growth inhibition exhibited by the feoB mutant in Fe‐deficient media was relieved by human holo‐transferrin, holo‐lactoferrin and Fe 3+ ‐dicitrate, but not by FeSO 4 . The feoB mutant had less cellular Fe and was more sensitive to growth inhibition by transition metals in comparison with the wild type. Biphasic kinetics of Fe 2+ transport in the wild type suggested the presence of high‐ and low‐affinity uptake systems. The high‐affinity system (apparent K s = 0.54 μM) is absent in the feoB mutant. Transport via FeoB is highly specific for Fe 2+ and was inhibited by FCCP, DCCD and vanadate, indicating an active process energized by ATP. Ferrozine inhibition of Fe 2+ and Fe 3+ uptake implied the concerted involvement of both an Fe 3+ reductase and FeoB in the uptake of Fe supplied as Fe 3+ . Taken together, the results are consistent with FeoB‐mediated Fe 2+ uptake being a major pathway for H. pylori Fe acquisition. feoB mutants were unable to colonize the gastric mucosa of mice, indicating that FeoB makes an important contribution to Fe acquisition by H. pylori in the low‐pH, low‐O 2 environment of the stomach.