E.p.r. and magnetic circular dichroism spectroscopic characterization of bacterioferritin from <i>Pseudomonas aeruginosa</i> and <i>Azotobacter vinelandii</i>

Cheesman, Myles R.; Kadir, Fahmi H.A.; Al-Basseet, Jamal; al-Massad, F K; Farrar, Jaqui A.; Greenwood, C. T.; Thomson, Andrew J.; Moore, G.R.

doi:10.1042/bj2860361

Cited by 45 publications

(30 citation statements)

References 25 publications

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“…Bacterioferritins differ from mammalian ferritins in that they have up to 12 noncovalently bound heme groups (4,39). The heme centers have bis-methionine ligation (12,13). Dps proteins have not been as thoroughly characterized as ferritins or bacterioferritins yet.…”

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confidence: 99%

Overexpression and Characterization of an Iron Storage and DNA-Binding Dps Protein from Trichodesmium erythraeum

Castruita¹,

Saito

Schottel³

et al. 2006

Appl Environ Microbiol

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Although the role of iron in marine productivity has received a great deal of attention, no iron storage protein has been isolated from a marine microorganism previously. We describe an Fe-binding protein belonging to the Dps family (DNA binding protein from starved cells) in the N 2 -fixing marine cyanobacterium Trichodesmium erythraeum. A dps gene encoding a protein with significant levels of identity to members of the Dps family was identified in the genome of T. erythraeum. This gene codes for a putative Dps T. erythraeurm protein (Dps tery ) with 69% primary amino acid sequence similarity to Synechococcus DpsA. We expressed and purified Dps tery , and we found that Dps tery , like other Dps proteins, is able to bind Fe and DNA and protect DNA from degradation by DNase. We also found that Dps tery binds phosphate, like other ferritin family proteins. Fe K near-edge X-ray absorption of Dps tery indicated that it has an iron core that resembles that of horse spleen ferritin.

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confidence: 99%

Overexpression and Characterization of an Iron Storage and DNA-Binding Dps Protein from Trichodesmium erythraeum

Castruita¹,

Saito

Schottel³

et al. 2006

Appl Environ Microbiol

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“…Furthermore, bacterioferritins differ from ferritins in possessing heme b prosthetic groups (up to 12 groups/24 subunits), which have a very low redox potential that depends on the presence (Ϫ475 mV) or absence (Ϫ225 mV) of an iron core (Watt et al, 1986). Magnetic circular dichroism (MCD), electron-paramagnetic resonance (EPR) spectroscopy, extended x-ray absorption fine structure, and x-ray crystallographic studies have shown that the heme iron of the bacterioferritins has a unique bis-methionine ligation (Cheesman et al, 1990(Cheesman et al, , 1992George et al, 1993;Frolow et al, 1994). Modeling studies suggested that the E. coli BFR possesses two potential heme-binding sites (site I and site II), each containing a pair of methionine residues correctly disposed to bind heme (Cheesman et al, 1993).…”

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confidence: 99%

Site-directed Replacement of the Coaxial Heme Ligands of Bacterioferritin Generates Heme-free Variants

Andrews

Brun

Barynin

et al. 1995

Journal of Biological Chemistry

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The bacterioferritin (BFR) of Escherichia coli is a heme-containing iron storage molecule. It is composed of 24 identical subunits, which form a roughly spherical protein shell surrounding a central iron storage cavity. Each of the 12 heme moieties of BFR possesses bis-methionine axial ligation, a heme coordination scheme so far only found in bacterioferritins. Members of the BFR family contain three partially conserved methionine residues (excluding the initiating methionine) and in this study each was substituted by leucine and/or histidine. The Met 52 variants were devoid of heme, whereas the Met 31 and Met 86 variants possessed full heme complements and were spectroscopically indistinguishable from wild-type BFR. The heme-free Met 52 variants appeared to be correctly assembled and were capable of accumulating iron both in vivo and in vitro. No major differences were observed in the overall rate of iron accumulation for BFR-M52H, BFR-M52L, and the wildtype protein. The iron contents of the Met 52 variants, as isolated, were at least 4 times greater than for wild-type BFR. This study is consistent with the reported location of the BFR heme site at the 2-fold axis and shows that heme is unnecessary for BFR assembly and iron uptake.

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“…Secondly, the cytochrome contains both haem and non-haem iron. Thirdly, the cytochrome contains protophorphyrin 1X coordinated by two methionine residues, so far a unique feature of bacterioferritins [45]. Fourthly, the first ten amino acids of the N-terminal sequence of its subunits show 70% sequence identity to bacterioferritin subunits from other bacteria.…”

Section: Discussionmentioning

confidence: 99%

“…1), characteristic of bis-methionine ligation of the haem [45]. Cytochrome b,,, was further analysed by PAGE and SDS/PAGE (data not shown).…”

Section: Cytochrome B Isolated From R Cupsulutus 37b4 Is a Bactermentioning

confidence: 99%

Iron metabolism in Rhodobacter capsulatus

Ringeling

Davy

Monkara

et al. 1994

European Journal of Biochemistry

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The water-soluble cytochrome b,,, from the photosynthetic bacterium Rhodobacter capsulatus was purified and shown to have the properties of the iron-storage protein bacterioferritin. The molecular mass of R. capsulatus bacterioferritin is 428 kDa and it is composed of a single type of 18-kDa subunit. The N-terminal amino acid sequence of the bacterioferritin subunit shows 70% identity to the sequence of bacterioferritin subunits from Escherichia coli, Nitrobacter winogradskyi, Azotobacter vinelandii and Synechocystis PCC 6803. The absorbance spectrum of reduced bacterioferritin shows absorbance maxima at 557 nm (a band), 526 nm @ band) and 417 nm (Soret band) from the six haem groups/molecule. Antibody assays reveal that bacterioferritin is located in the cytoplasm of R. capsulatus, and its levels stay relatively constant during batch growth under aerobic conditions when the iron concentration in the medium is kept constant. Iron deficiency leads to a decrease in bacterioferritin and iron overload leads to an increase. Bacterioferritin from R. capsulatus has an amorphous iron-oxide core with a high phosphate content (900-1000 Fe atoms and approximately 600 phosphateshacterioferritin molecule). Mossbauer spectroscopy indicates that in both aerobically and anaerobically (phototrophically) grown cells bacterioferritin with an Fe'+ core is formed, suggesting that iron-core formation in vivo may not always require molecular oxygen.Iron is an essential element for the growth of almost all bacteria and many of the molecular details of iron uptake have been established [l -51. The intracellular sequestration and mobilisation of iron have received little attention but a potential iron store which has been identified in Azotobacter vinelandii [6] [6,9, 101. N-terminal amino acid sequences of bacterioferritin polypeptides are highly similar [lo-141 and the molecular properties of these proteins indicate that they form a closely related family. Bacterioferritin, like its animal counterpart ferritin, is organised as a hollow protein shell which can contain a non-haem iron in its central cavity [6,[15][16][17]. Unlike mammalian ferritin, in which the non-haem iron core is crystalline ferrihydrite [16, 181, bacterioferritin has an amorphous iron core with a high phosphate content [19]. Another difference between mammalian fenitins and bacterioferritins is that the latter contain intrinsic haem groups while the former do not. It is the presence of haem in purified Alternative bacterial iron-storage systems to bacterioferritin exist. Fenitin of the non-haem type, with a relatively high sequence similarity to animal fenitin, has been isolated from Helicobacter pylori [21] and Bacteroides fragilis [22], and its gene has been cloned from E. coli [23]. Furthermore, the 57Fe Mossbauer spectroscopy study of intact E. coli cells reported by Matzanke et al. [24] clearly identified two ironrich species present in greater quantity than bacterioferritin that might constitute a novel iron-storage system.No iron-storage protein has been pr...

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E.p.r. and magnetic circular dichroism spectroscopic characterization of bacterioferritin from Pseudomonas aeruginosa and Azotobacter vinelandii

Cited by 45 publications

References 25 publications

Overexpression and Characterization of an Iron Storage and DNA-Binding Dps Protein from Trichodesmium erythraeum

Overexpression and Characterization of an Iron Storage and DNA-Binding Dps Protein from Trichodesmium erythraeum

Site-directed Replacement of the Coaxial Heme Ligands of Bacterioferritin Generates Heme-free Variants

Iron metabolism in Rhodobacter capsulatus

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