Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Isolation of a ferritin from Bacteroides fragilis (1992)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 95 (1992), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract A ferritin was isolated from the obligate anaerobe Bacteroides fragilis. Estimated molecular masses were 400 kDa for the holomer and 16.7 kDa for the subunits. A 30-residue N-terminal amino acid sequence was determined and found to resemble the sequences of other ferritins (human H-chain ferritin, 43% identity; Escherichia coli gen-165 product, 37% identity) and to a lesser degree, bacterioferritins (E. coli bacterioferritin, 20% identity). The protein stained positively for iron, and incorporated 59Fe when B. fragilis was grown in the presence of [59Fe]citrate. However, the isolated protein contained only about three iron atoms per molecule, and contained no detectable haem. This represents the first isolation of a ferritin protein from bacteria. It may alleviate iron toxicity in the presence of oxygen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1992.tb05367.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Bacterial iron homeostasis (2003)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology reviews 27 (2003), S. 0 
    Details
    ISSN: 1574-6976
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Iron is essential to virtually all organisms, but poses problems of toxicity and poor solubility. Bacteria have evolved various mechanisms to counter the problems imposed by their iron dependence, allowing them to achieve effective iron homeostasis under a range of iron regimes. Highly efficient iron acquisition systems are used to scavenge iron from the environment under iron-restricted conditions. In many cases, this involves the secretion and internalisation of extracellular ferric chelators called siderophores. Ferrous iron can also be directly imported by the G protein-like transporter, FeoB. For pathogens, host–iron complexes (transferrin, lactoferrin, haem, haemoglobin) are directly used as iron sources. Bacterial iron storage proteins (ferritin, bacterioferritin) provide intracellular iron reserves for use when external supplies are restricted, and iron detoxification proteins (Dps) are employed to protect the chromosome from iron-induced free radical damage. There is evidence that bacteria control their iron requirements in response to iron availability by down-regulating the expression of iron proteins during iron-restricted growth. And finally, the expression of the iron homeostatic machinery is subject to iron-dependent global control ensuring that iron acquisition, storage and consumption are geared to iron availability and that intracellular levels of free iron do not reach toxic levels.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/S0168-6445(03)00055-X
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Topological analysis of DctQ, the small integral membrane protein of the C4-dicarboxylate TRAP transporter of Rhodobacter capsulatus (2001)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 194 (2001), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Tripartite ATP-independent periplasmic (‘TRAP’) transporters are a novel group of bacterial and archaeal secondary solute uptake systems which possess a periplasmic binding protein, but which are unrelated to ATP-binding cassette (ABC) systems. In addition to the binding protein, TRAP transporters contain two integral membrane proteins or domains, one of which is 40–50 kDa with 12 predicted transmembrane (TM) helices, thought to be the solute import protein, while the other is 20–30 kDa and of unknown function. Using a series of plasmid-encoded β-lactamase fusions, we have determined the topology of DctQ, the smaller integral membrane protein from the high-affinity C4-dicarboxylate transporter of Rhodobacter capsulatus, which to date is the most extensively characterised TRAP transporter. DctQ was predicted by several topology prediction programmes to have four TM helices with the N- and C-termini located in the cytoplasm. The levels of ampicillin resistance conferred by the fusions when expressed in Escherichia coli were found to correlate with this predicted topology. The data have provided a topological model which can be used to test hypotheses concerning the function of the different regions of DctQ and which can be applied to other members of the DctQ family.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.2001.tb09439.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Iron acquisition and virulence in Helicobacter pylori: a major role for FeoB, a high-affinity ferrous iron transporter (2000)
    Oxford, UK : Blackwell Science Ltd
    Molecular microbiology 37 (2000), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The genome sequence of Helicobacter pylori suggests that this bacterium possesses several Fe acquisition systems, including both Fe2+- and Fe3+-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 Fe2+ or Fe3+ form. In contrast, transport rates were unaffected by the other mutations. Complementation of the feoB mutation fully restored both Fe2+ and Fe3+ transport. The growth inhibition exhibited by the feoB mutant in Fe-deficient media was relieved by human holo-transferrin, holo-lactoferrin and Fe3+-dicitrate, but not by FeSO4. 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 Fe2+ transport in the wild type suggested the presence of high- and low-affinity uptake systems. The high-affinity system (apparent Ks = 0.54 μM) is absent in the feoB mutant. Transport via FeoB is highly specific for Fe2+ and was inhibited by FCCP, DCCD and vanadate, indicating an active process energized by ATP. Ferrozine inhibition of Fe2+ and Fe3+ uptake implied the concerted involvement of both an Fe3+ reductase and FeoB in the uptake of Fe supplied as Fe3+. Taken together, the results are consistent with FeoB-mediated Fe2+ 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-O2 environment of the stomach.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.2000.01987.x
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Ferritin subunits in livers of siderotic mice (1989)
    Springer
    BioMetals 2 (1989), S. 77-82 
    Details
    ISSN: 1572-8773
    Keywords: Ferritin ; Siderotic mice ; Amino acid sequence ; L subunit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary The major ferritin species of mouse liver has been resolved by SDS-PAGE into two bands similar to the H and L subunits of rat liver ferritin with the L subunit predominating. Amino acid sequencing has confirmed the major, faster-migrating component as L chain. An additional, electrophoretically fast, minor ferritin was isolated from siderosome-containing subcellular fractions. In denaturing gels it gave a single ‘F’ subunit band of about 17 kDa, significantly smaller than the L and H subunits (about 20 and 21 kDa respectively). A small fragment isolated from the fast ferritin was sequenced. It corresponds to a 19-residue C-terminal peptide cleaved from L subunits in the assembled molecules. The F subunit must be derived from L subunits by loss of this peptide, and is not the expression product of a different gene. ‘Fast’ ferritins of siderotic mice and rats are thus analogous.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01129204
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Mössbauer spectroscopy and electron paramagnetic resonance studies of iron metabolites inPseudomonas aeruginosa: Fe2+ and Fe3+ ferritin in57ferripyoverdine incubated cells and57ferric citrate fed cells (1992)
    Springer
    BioMetals 5 (1992), S. 87-93 
    Details
    ISSN: 1572-8773
    Keywords: Mössbauer ; EPR ; ferritin ; ferripyoverdine ; Pseudomonas aeruginosa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Pseudomonas aeruginosa samples were studied using Mössbauer spectroscopy and electron paramagnetic resonance (EPR). Samples included whole cells, membranes, and soluble fractions from cells which had been grown with57ferric chloride,57ferric citrate or incubated with57ferripyoverdine. These experiments show for the first time thatP. aeruginosa can accumulate iron in a bacterioferritin when grown under conditions of iron limitation and incubated with its cognate ferrisiderophore, ferripyoverdine. Soluble fraction fromP. aeruginosa cells which were grown iron starved and incubated with57ferripyoverdine for 120 min showed the presence of both a ferric and ferrous complex whose Mössbauer spectra matched that of bacterioferritin extracted fromAzotobacter vinelandii and whose EPR spectra showed a characteristic ferritin-like resonance. A second soluble fraction sample from cells which had been grown with57ferric citrate also showed the presence of a species with the same EPR and Mössbauer parameters. In addition Western blotting confirmed the presence of bacterioferritin in the soluble fraction of the cells which had been incubated with ferripyoverdine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01062219
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Studies on haemosiderin and ferritin from iron-loaded rat liver (1988)
    Springer
    BioMetals 1 (1988), S. 33-42 
    Details
    ISSN: 1572-8773
    Keywords: Haemosiderin ; Ferritin ; Iron ; Rat liver
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary Haemosiderin has been isolated from siderosomes and ferritin from the cytosol of livers of rats iron-loaded by intraperitoneal injections of iron-dextran. Siderosomal haermosiderin, like ferritin, was shown by electron diffraction to contain iron mainly in the form of small particles of ferrihydrite (5Fe2O3 · 9H2O), with average particle diameter of 5.36±1.31 nm (SD), less than that of ferritin iron-cores (6.14±1.18 nm). Mössbauer spectra of both iron-storage complexes are also similar, except that the blocking temperature,T B, for haemosiderin (23 K) is lower than that of ferritin (35 K). These values are consistent with their differences in particle volumes assuming identical magnetic anisotropy constants. Measurements of P/Fe ratios by electron probe microanalysis showed the presence of phosphorus in rat liver haemosiderin, but much of it was lost on extensive dialysis. The presence of peptides reacting with anti-ferritin antisera and the similarities in the structures of their iron components are consistent with the view that rat liver haemosiderin arises by degradation of ferritin polypeptides, but its peptide pattern is different from that found in humanβ-thalassaemia haemosiderin. The blocking temperature, 35 K, for rat liver ferritin is near to that reported, 40 K, for humanβ-thalassaemia spleen ferritin. However, the haemosiderin isolated from this tissue, in contrast to that from rat liver, had aT B higher than that of ferritin. The iron availability of haemosiderins from rat liver and humanβ-thalassaemic spleen to a hydroxypyridinone chelator also differed. That from rat liver was equal to or greater, and that from human spleen was markedly less, than the iron availability from either of the associated ferritins, which were equivalent. The differences in properties of the two types of haemosiderin may reflect their origins from primary or secondary iron overload and differences in the duration of the overload.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01128015
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...