Iron and virulence in <i>Shigella</i>

Payne, Shelley M.

doi:10.1111/j.1365-2958.1989.tb00281.x

Cited by 57 publications

(38 citation statements)

References 31 publications

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“…Similarly, it has been shown for aerobactin-defective mutants of Shigella spp. that they are not altered in their virulence (20), and it has been speculated that heme may be a source of iron for these intracellular pathogens (24). We think that also, in this case, ferrous iron has to be considered as an important additional source.…”

Section: Discussionmentioning

confidence: 99%

Characterization of the ferrous iron uptake system of Escherichia coli

1993

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Escherichia coli has an iron(II) transport system (feo) which may make an important contribution to the iron supply of the cell under anaerobic conditions. Cloning and sequencing of the iron(II) transport genes revealed an open reading frame (feoA) possibly coding for a small protein with 75 amino acids and a membrane protein with 773 amino acids (feoB). The upstream region offeoAB contained a binding site for the regulatory protein Fur, which acts with iron(ll) as a corepressor in all known iron transport systems ofE. coli. In addition, a Fnr binding site was identified in the promoter region. The FeoB protein had an apparent molecular mass of 70 kDa in sodium dodecyl sulfate-polyacrylamide gel electrophoresis and was localized in the cytoplasmic membrane.The sequence revealed regions of homology to ATPases, which indicates that ferrous iron uptake may be ATP driven. FeoA or FeoB mutants could be complemented by clones with the feoA orfeoB gene, respectively.Since iron(III) is practically insoluble at neutral pH, many aerobic microorganisms secrete siderophores, iron(III) chelating compounds, for their iron supply. Six different siderophore-iron(III) transport systems in Escherichia coli have been sequenced and analyzed, and many more in other gram-negative bacteria have been characterized (4). These transport systems share a common structure. A ferric siderophore-specific receptor in the outer membrane delivers its substrate in an energy-dependent mechanism to the periplasm. The energy is provided by the TonB-ExbB-ExbD complex (4). Even heme (33) and transferrin iron (6) are taken up in a TonB-dependent manner. With

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Section: Discussionmentioning

confidence: 99%

Characterization of the ferrous iron uptake system of Escherichia coli

1993

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“…Excess iron increases the virulence of organisms as diverse as Escherichia (9), Klebsiella (10), Listeria (11), Neisseria (12), Pasteurella (11), Shigella (13), Salmonella (14,15), Vibrio (16), and Yersinia (17). Iron dextran injections in children, originally intended to prevent iron deficiencies, enhanced Escherichia coli bacteremia and meningitis (18).…”

Section: Iron: Can't Live With It Can't Live Without Itmentioning

confidence: 99%

Enterobactin: An archetype for microbial iron transport

Raymond

Dertz

Kim

2003

Proc. Natl. Acad. Sci. U.S.A.

805

692

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Bacteria have aggressive acquisition processes for iron, an essential nutrient. Siderophores are small iron chelators that facilitate cellular iron transport. The siderophore enterobactin is a triscatechol derivative of a cyclic triserine lactone. Studies of the chemistry, regulation, synthesis, recognition, and transport of enterobactin make it perhaps the best understood of the siderophore-mediated iron uptake systems, displaying a lot of function packed into this small molecule. However, recent surprises include the isolation of corynebactin, a closely related trithreonine triscatechol derivative lactone first found in Gram-positive bacteria, and the crystal structure of a ferric enterobactin complex of a protein identified as an antibacterial component of the human innate immune system.

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“…The Vibrio cholerae fur gene has been characterized (40,41) and has been shown to regulate the expression of two virulence-associated genes, irgA and viuA (11,25). Gene regulation by a Fur protein also occurs in Yersinia pestis (56,57), Salmonella typhimurium (21,22), Neisseria gonorrhoeae (4), Neisseria meningitidis (38); Shigella species (47), Bordetella species (7), Legionella pneumophila (33), Campylobacter jejuni (65), and Pseudomonas species (46,60). We previously reported on the identification of a Fur homolog in Pseudomonas aeruginosa, referred to as PA-Fur, and on the cloning and sequencing of the fur gene (49,50).…”

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confidence: 99%

Role of the ferric uptake regulator of Pseudomonas aeruginosa in the regulation of siderophores and exotoxin A expression: purification and activity on iron-regulated promoters

1995

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The cloned Pseudomonas aeruginosa fur (ferric uptake regulator) gene was overexpressed in P. aeruginosa by using a T7 expression system, and the Fur protein (PA-Fur) was purified by using a combination of ionexchange chromatography and metal affinity chromatography. The DNA binding activity of the PA-Fur protein was confirmed by gel mobility shift assays and DNase I footprints of the synthetic DNA fragment GATAAT GATAATCATTATC, representing a perfect ''Fur box''. In addition, it was shown that PA-Fur is capable of binding to promoter and operator determinants of the tightly iron-regulated Escherichia coli fepA-fes enterobactin gene system. The activity of PA-Fur on the promoters of iron-regulated genes involved in the production of two siderophores, pyochelin and pyoverdin, and in the expression of exotoxin A was investigated. Data indicating that the promoters of the pchR gene, encoding a transcriptional activator for pyochelin synthesis, and of the pvdS gene, encoding a positive regulator for pyoverdin production, are specifically recognized by Fur-Fe(II) are presented, suggesting that PA-Fur represses expression of pchR and pvdS during growth in an iron-replete environment. However, neither the promoter region of the gene encoding exotoxin A (toxA) nor the promoters of the regAB operon, required for toxA expression, interacted with high concentrations of purified PA-Fur. These data indicate that iron regulation of exotoxin A production involves additional factors which may ultimately be under the control of PA-Fur.

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Iron and virulence in Shigella

Cited by 57 publications

References 31 publications

Characterization of the ferrous iron uptake system of Escherichia coli

Characterization of the ferrous iron uptake system of Escherichia coli

Enterobactin: An archetype for microbial iron transport

Role of the ferric uptake regulator of Pseudomonas aeruginosa in the regulation of siderophores and exotoxin A expression: purification and activity on iron-regulated promoters

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