scholarly journals High-affinity binding by the periplasmic iron-binding protein from Haemophilus influenzae is required for acquiring iron from transferrin

2007 ◽  
Vol 404 (2) ◽  
pp. 217-225 ◽  
Author(s):  
Ali G. Khan ◽  
Stephen R. Shouldice ◽  
Shane D. Kirby ◽  
Rong-hua Yu ◽  
Leslie W. Tari ◽  
...  
Keyword(s):  
Haemophilus Influenzae ◽  
Metal Binding ◽  
Binding Assay ◽  
Rank Order ◽  
Binding Protein ◽  
Iron Binding ◽  
Wild Type ◽  
Mutant Proteins ◽  
High Affinity ◽  
Iron Binding Protein

The periplasmic iron-binding protein, FbpA (ferric-ion-binding protein A), performs an essential role in iron acquisition from transferrin in Haemophilus influenzae. A series of site-directed mutants in the metal-binding amino acids of FbpA were prepared to determine their relative contribution to iron binding and transport. Structural studies demonstrated that the mutant proteins crystallized in an open conformation with the iron atom associated with the C-terminal domain. The iron-binding properties of the mutant proteins were assessed by several assays, including a novel competitive iron-binding assay. The relative ability of the proteins to compete for iron was pH dependent, with a rank order at pH 6.5 of wild-type, Q58L, H9Q>H9A, E57A>Y195A, Y196A. The genes encoding the mutant FbpA were introduced into H. influenzae and the resulting strains varied in the level of ferric citrate required to support growth on iron-limited medium, suggesting a rank order for metal-binding affinities under physiological conditions comparable with the competitive binding assay at pH 6.5 (wild-type=Q58L>H9Q>H9A, E57A>Y195A, Y196A). Growth dependence on human transferrin was only obtained with cells expressing wild-type, Q58L or H9Q FbpAs, proteins with stability constants derived from the competition assay >2.0×1018 M−1. These results suggest that a relatively high affinity of iron binding by FbpA is required for removal of iron from transferrin and its transport across the outer membrane.

scholarly journals An Iron-Binding Protein, Dpr, Decreases Hydrogen Peroxide Stress and Protects Streptococcus pyogenes against Multiple Stresses

2008 ◽  
Vol 76 (9) ◽  
pp. 4038-4045 ◽  
Author(s):  
Chih-Cheng Tsou ◽  
Chuan Chiang-Ni ◽  
Yee-Shin Lin ◽  
Woei-Jer Chuang ◽  
Ming-T. Lin ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Streptococcus Pyogenes ◽  
Type Strain ◽  
Wild Type Strain ◽  
Binding Protein ◽  
Binding Activity ◽  
Iron Binding ◽  
Wild Type ◽  
Iron Binding Protein ◽  
Peroxide Stress

ABSTRACT Streptococcus pyogenes does not produce catalase, but it can grow in aerobic environments and survive in the presence of peroxide. One of the stress proteins of this organism, peroxide resistance protein (Dpr), has been studied to examine its role in resistance to hydrogen peroxide, but the protective mechanism of Dpr is not clear. The aim of this study was to characterize the dpr gene and its role in dealing with different stresses. A dpr deletion mutant was constructed by double-crossover mutagenesis. The dpr mutant was more sensitive to H2O2, and complementation could partially restore the defect in the mutant. Pretreatment with the iron chelator deferoxamine mesylate rescued the survival activity of the mutant under oxidative stress conditions. The dpr mutant also showed a low survival rate in the long-term stationary phase, when it was treated with extreme acids, and under alkaline pH conditions compared to the wild-type strain. The growth of the dpr mutant was slower than that of the wild-type strain in iron-limiting conditions. The dpr mutant showed high sensitivity to iron and zinc but not to manganese, copper, nickel, and calcium. Recombinant Dpr protein was purified and showed iron-binding activity, whereas no DNA-binding activity was found. These data indicate that an iron-binding protein, Dpr, provides protection from hydrogen peroxide stress by preventing the Fenton reaction, and Dpr was identified as a novel stress protein that protects against several stresses in group A streptococci.

Employment of Iron-Binding Protein from Haemophilus influenzae in Functional Nanopipettes for Iron Monitoring

2018 ◽  
Vol 10 (4) ◽  
pp. 1970-1977
Author(s):  
Gonca Bulbul ◽  
Goksin Liu ◽  
Namrata Rao Vithalapur ◽  
Canan Atilgan ◽  
Zehra Sayers ◽  
...  
Keyword(s):  
Haemophilus Influenzae ◽  
Binding Protein ◽  
Iron Binding ◽  
Iron Binding Protein

scholarly journals Lactoferrin-an iron binding protein in synovial fluid

1973 ◽  
Vol 16 (2) ◽  
pp. 186-190 ◽  
Author(s):  
Robert M Bennett ◽  
A C Eddie-Quartey ◽  
P J L Holt
Keyword(s):  
Synovial Fluid ◽  
Binding Protein ◽  
Iron Binding ◽  
Iron Binding Protein

scholarly journals Iron-Binding Protein of Swine Serum.

1947 ◽  
Vol 1 ◽  
pp. 770-776 ◽  
Author(s):  
C.-B Laurell ◽  
B. Ingelman
Keyword(s):  
Binding Protein ◽  
Iron Binding ◽  
Iron Binding Protein ◽  
Swine Serum

scholarly journals IRON METABOLISM

Blood ◽  
1950 ◽  
Vol 5 (11) ◽  
pp. 983-1008 ◽  
Author(s):  
CLEMENT A. FINCH ◽  
MARK HEGSTED ◽  
THOMAS D. KINNEY ◽  
E. D. THOMAS ◽  
CHARLES E. RATH ◽  
...  
Keyword(s):  
Iron Metabolism ◽  
Serum Iron ◽  
Iron Absorption ◽  
Binding Protein ◽  
The Body ◽  
Iron Binding ◽  
Body Iron ◽  
Iron Administration ◽  
Parenteral Iron ◽  
Iron Binding Protein

Abstract On the basis of experimental and clinical observations and a review of the literature, a concept of the behavior of storage iron in relation to body iron metabolism has been formulated. Storage iron is defined as tissue iron which is available for hemoglobin synthesis when the need arises. This iron is stored intracellularly in protein complex as ferritin and hemosiderin. It would appear that wherever the cell is functionally intact, such iron is available for general body needs. Iron is transported by a globulin of the serum to and from the various tissues of the body to satisfy their metabolism. Surplus iron carried by this iron-binding protein is deposited chiefly in the liver. Storage iron may be increased in two ways. The first mechanism results from the inability of the body to excrete significant amounts of iron. Because of this, any decrease in circulating red cell iron (any anemia other than blood loss or iron deficiency anemia) is accompanied by a shift of iron to the tissue compartment. The total amount of body iron remains constant and is merely redistributed. This is to be contrasted with the absolute increase in body iron and enlarged iron stores which follow excessive iron absorption or parenteral iron administration. Enlarged iron stores in either instance may be evaluated by examination of sternal marrow or determination of the serum iron and saturation of the iron binding protein In states of iron excess, differences in initial distribution are observed, depending on the route of administration and type of iron compound employed. Iron absorbed from the gastro-intestinal tract and soluble iron salts injected in small amounts are transported by the iron-binding protein of the serum and stored predominantly in the liver. Colloidal iron given intravenously is taken up by the reticulo-endothelial tissue. Erythrocytes appear to localize in greatest concentration in the spleen, while greater amounts of hemoglobin iron are found in the renal parenchyma. These latter differences in distribution reflect the capacity of various body tissues to assimilate different iron compounds, which while present in the plasma are not carried by the iron-binding protein. Over a period of time an internal redistribution of iron from these various sites occurs through the serum iron compartment. The liver becomes progressively loaded with iron. When the capacity of the liver to store iron is exceeded, the serum iron increases and secondary tissue receptors begin to fill with iron. That iron in large amounts is toxic to tissues is suggested by the occurrence of fibrosis in the organs most heavily laden with iron. This sequence of events, whether following excessive iron absorption or parenteral iron administration is believed to be responsible for the clinical and pathologic picture of hemochromatosis.

scholarly journals The superoxide-dependent transfer of iron from ferritin to transferrin and lactoferrin

1988 ◽  
Vol 256 (3) ◽  
pp. 923-928 ◽  
Author(s):  
H P Monteiro ◽  
C C Winterbourn
Keyword(s):  
Lipid Peroxidation ◽  
Free Radicals ◽  
Xanthine Oxidase ◽  
Binding Protein ◽  
Gel Filtration ◽  
Iron Binding ◽  
Oxidase System ◽  
Oxidative Reactions ◽  
Phospholipid Liposomes ◽  
Iron Binding Protein

By the use of gel filtration and [59Fe]ferritin, apotransferrin and apolactoferrin were shown to take up iron released from ferritin by superoxide generated by hypoxanthine and xanthine oxidase. Apotransferrin also inhibited uptake of released iron by ferrozine. Ferritin and the xanthine oxidase system induced lipid peroxidation in phospholipid liposomes. This peroxidation was inhibited by apotransferrin or apolactoferrin. Thus, although superoxide and other free radicals can release iron from ferritin, either iron-binding protein, if present, should take up this iron and prevent its catalysing subsequent oxidative reactions.

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