scholarly journals Characterization of iron binding in IscA, an ancient iron-sulphur cluster assembly protein

2004 ◽  
Vol 379 (2) ◽  
pp. 433-440 ◽  
Author(s):  
Huangen DING ◽  
Robert J. CLARK
Keyword(s):  
Association Constant ◽  
Binding Protein ◽  
Iron Binding ◽  
Cluster Assembly ◽  
Intracellular Iron ◽  
Ancient Iron ◽  
Iron Binding Protein ◽  
Redox Centre

Iron–sulphur clusters are one of the most common types of redox centre in biology. At least six proteins (IscS, IscU, IscA, HscB, HscA and ferredoxin) have been identified as being essential for the biogenesis of iron–sulphur proteins in bacteria. It has been shown that IscS is a cysteine desulphurase that provides sulphur for iron–sulphur clusters, and that IscU is a scaffold for the IscS-mediated assembly of iron–sulphur clusters. The iron donor for iron–sulphur clusters, however, remains elusive. Here we show that IscA is an iron binding protein with an apparent iron association constant of 3.0×1019 M−1, and that iron-loaded IscA can provide iron for the assembly of transient iron–sulphur clusters in IscU in the presence of IscS and l-cysteine in vitro. The results suggest that IscA is capable of recruiting intracellular iron and delivering iron for iron–sulphur clusters in proteins.

scholarly journals Identification of lactoferrin as the granulocyte-derived inhibitor of colony-stimulating activity production.

1978 ◽  
Vol 148 (4) ◽  
pp. 1052-1067 ◽  
Author(s):  
H E Broxmeyer ◽  
A Smithyman ◽  
R R Eger ◽  
P A Meyers ◽  
M de Sousa
Keyword(s):  
Binding Protein ◽  
Iron Binding ◽  
Blood Monocytes ◽  
Iron Saturation ◽  
Colony Stimulating Activity ◽  
Monocytes And Macrophages ◽  
Iron Binding Protein ◽  
Macrophage Colony

Lactoferrin (LF), the iron-binding protein present in the specific granules of mature granulocytes has been identified as colony inhibitory factor (CIF) which suppresses granulocyte--macrophage colony stimulating activity (CSA) production by monocytes and macrophages in vitro and rebound granulopoiesis in vivo. Separation of LF and CIF by isoelectric focusing confirmed that the regions of inhibitory activity corresponded in both to a pH of congruent to 6.5. In addition, the purified immunoglobulin fraction of rabbit anti-human LF antiserum, but not rabbit anti-transferrin (TF), inactivated the capacity of LF and CIF to inhibit CSA production, an effect blocked by prior incubation of anti-LF with neutralizing concentrations of LF. Suppression of CSA production correlated with the iron-saturation of LF; APO-LF (depleted of iron) was only active concentrations greater than 10(-7) M, native LF (8% iron saturated) was active at 10(-15) M, and fully iron-saturated LF inhibited at 10(-17) M. Suppression of CSA production occurred within a 1/2-h preincubation period with human blood monocytes but was reversed by bacterial lipopolysaccharide (LPS). This reversal was dependent on the relative concentrations of LF to LPS. Serum TF, a biochemically similar iron-binding protein which is antigenically distinct from LF, was only minimally active at concentrations greater than 10(-6) M. LF did not inhibit exogenously stimulated human granylocyte and macrophage colony-forming cells or erythropoietin-dependent human or murine erythroid colony- or erythroid burst-forming cells. Microgram quantities of LF acted in vivo to inhibit rebound granulopoiesis and CSA production in CD1 and C57Bl/6 mice pretreated with cyclophosphamide. These results strongly implicate LF as a physiological regulator of granulopoiesis.

scholarly journals Mobilization of the iron centre in IscA for the iron–sulphur cluster assembly in IscU

2005 ◽  
Vol 389 (3) ◽  
pp. 797-802 ◽  
Author(s):  
Baojin Ding ◽  
Edward S. Smith ◽  
Huangen Ding
Keyword(s):  
Escherichia Coli ◽  
Reduced Glutathione ◽  
Binding Protein ◽  
Iron Binding ◽  
Cluster Assembly ◽  
Uv Visible ◽  
Iron Binding Protein ◽  
Epr Measurements

The biogenesis of iron–sulphur clusters requires the co-ordinated delivery of both iron and sulphur. It is now clear that sulphur in iron–sulphur clusters is derived from L-cysteine by cysteine desulphurases. However, the iron donor for the iron–sulphur cluster assembly still remains elusive. Our previous studies indicated that Escherichia coli IscA, a member of the iron–sulphur cluster assembly machinery, is an iron-binding protein that can provide iron for the iron–sulphur cluster assembly in a proposed scaffold IscU. To determine how the iron centre in IscA is transferred for the iron–sulphur cluster assembly in IscU, we explore the mobility of the iron centre in IscA. The UV–visible and EPR measurements show that L-cysteine, but not IscU, is able to mobilize the iron centre in IscA and make the iron available for the iron–sulphur cluster assembly in IscU. Other related biological thiols such as N-acetyl-L-cysteine or reduced glutathione have no effect on the iron centre of IscA, suggesting that L-cysteine is unique in mobilizing the iron centre of IscA. Nevertheless, L-cysteine alone is not sufficient to transfer the iron from IscA to IscU. Both L-cysteine and cysteine desulphurase (IscS) are required for the IscA-mediated assembly of iron–sulphur clusters in IscU. The results suggest that L-cysteine may have two distinct functions in the biogenesis of iron–sulphur clusters: to mobilize the iron centre in IscA and to provide sulphur via cysteine desulphurase (IscS) for the iron–sulphur cluster assembly in IscU.

scholarly journals An Iron-Binding Protein, Dpr, from Streptococcus mutans Prevents Iron-Dependent Hydroxyl Radical Formation In Vitro

2002 ◽  
Vol 184 (11) ◽  
pp. 2931-2939 ◽  
Author(s):  
Yuji Yamamoto ◽  
Leslie B. Poole ◽  
Roy R. Hantgan ◽  
Yoshiyuki Kamio
Keyword(s):  
Hydroxyl Radical ◽  
Streptococcus Mutans ◽  
Analytical Ultracentrifugation ◽  
Binding Protein ◽  
Iron Binding ◽  
E Coli ◽  
Iron And Zinc ◽  
A Subunit ◽  
Iron Binding Protein

ABSTRACT The dpr gene is an antioxidant gene which was isolated from the Streptococcus mutans chromosome by its ability to complement an alkyl hydroperoxide reductase-deficient mutant of Escherichia coli, and it was proven to play an indispensable role in oxygen tolerance in S. mutans. Here, we purified the 20-kDa dpr gene product, Dpr, from a crude extract of S. mutans as an iron-binding protein and found that Dpr formed a spherical oligomer about 9 nm in diameter. Molecular weight determinations of Dpr in solution by analytical ultracentrifugation and light-scattering analyses gave values of 223,000 to 292,000, consistent with a subunit composition of 11.5 to 15 subunits per molecule. The purified Dpr contained iron and zinc atoms and had an ability to incorporate up to 480 iron and 11.2 zinc atoms per molecule. Unlike E. coli Dps and two other members of the Dps family, Dpr was unable to bind DNA. One hundred nanomolar Dpr prevented by more than 90% the formation of hydroxyl radical generated by 10 μM iron(II) salt in vitro. The data shown in this study indicate that Dpr may act as a ferritin-like iron-binding protein in S. mutans and may allow this catalase- and heme-peroxidase-deficient bacterium to grow under air by limiting the iron-catalyzed Fenton reaction.

Molecular characterization of the iron binding protein ferritin in Eisenia andrei earthworms

Gene ◽  
2011 ◽  
Vol 485 (2) ◽  
pp. 73-80 ◽  
Author(s):  
Petra Procházková ◽  
Jiří Dvořák ◽  
Marcela Šilerová ◽  
Radka Roubalová ◽  
František Škanta ◽  
...  
Keyword(s):  
Molecular Characterization ◽  
Binding Protein ◽  
Iron Binding ◽  
Eisenia Andrei ◽  
Iron Binding Protein

The iron-binding protein ferritin is expressed in cells of the osteoblastic lineage in vitro and in vivo

Bone ◽  
1995 ◽  
Vol 17 (2) ◽  
pp. 161-165 ◽  
Author(s):  
M. Spanner ◽  
K. Weber ◽  
B. Lanske ◽  
A. Ihbe ◽  
H. Siggelkow ◽  
...  
Keyword(s):  
Binding Protein ◽  
Iron Binding ◽  
Osteoblastic Lineage ◽  
Iron Binding Protein ◽  
In Cells

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
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