ConspectusDespite its essentiality to life, iron presents significant challenges cells: the exceedingly low solubility of Fe3+ limits bioavailability, and reactivity Fe2+ toward H2O2 is a source toxic hydroxyl radical (HO•). Consequently, cellular levels free are highly regulated ensure sufficiency while preventing iron-induced toxicity. Relatively little known about fate in bacterial cytosol or how cells balance need for relatively high cytosolic concentrations with potential toxicity...

Ferritin-like molecules are unique to cellular iron homeostasis because they can store at concentrations much higher than those dictated by the solubility of Fe(3+). Very little is known about protein interactions that deliver for storage or promote mobilization stored from ferritin-like molecules. Here, we report X-ray crystal structure Pseudomonas aeruginosa bacterioferritin (Pa-BfrB) in complex with bacterioferritin-associated ferredoxin (Pa-Bfd) 2.0 Å resolution. As first example a...

Meso-2,3-dimercaptosuccinic acid (DMSA) is bound to plasma albumin in humans and appears be excreted the urine as DMSA-cysteine mixed disulfide. The pharmacokinetics of DMSA have been determined after its administration po. For blood, tmaxand tl/2 were 3.0 h + 0.45 SE 3.2 0.56 SE, respectively. Cmax was 26.2 μM 4.7 SE. To determine whether dental amalgams influence human body burden mercury, we gave volunteers sodium salt 2,3-dimer-captopropane-1-sulfonic (DMPS). diameters subjects obtain...

For many pathogenic bacteria like Pseudomonas aeruginosa heme is an essential source of iron. After uptake, the molecule degraded by oxygenases to yield iron, carbon monoxide, and biliverdin. The oxygenase PigA only induced under iron-limiting conditions produces unusual biliverdin isomers IXbeta IXdelta. gene for a second putative in P. aeruginosa, bphO, occurs operon with bphP encoding bacterial phytochrome. Here we provide biochemical evidence that bphO encodes aeruginosa. HPLC, (1)H,...

Phytochromes are a collection of bilin-containing photoreceptors that regulate diverse array processes in microorganisms and plants through photoconversion between two stable states, red light-absorbing Pr form, far Pfr form. Recently, novel set phytochrome-like chromoproteins was discovered cyanobacteria, designated here as cyanochromes, instead photoconvert blue green forms Pb Pg, respectively. Here, we show the distinctive absorption properties cyanochromes facilitated binding...

The bfrB gene from Pseudomonas aeruginosa was cloned and expressed in Escherichia coli. resultant protein (BfrB), which assembles into a 445.3 kDa complex 24 identical subunits, binds 12 molecules of heme axially coordinated by two Met residues. BfrB, isolated with 5-10 iron atoms per molecule, reconstituted ferrous ions to prepare samples core mineral containing 600 +/- 40 ferric BfrB molecule approximately one phosphate atom. In the presence sodium dithionite or P. ferredoxin NADP...

The structure of recombinant Pseudomonas aeruginosa bacterioferritin B (Pa BfrB) has been determined from crystals grown protein devoid core mineral iron (as-isolated) and mineralized with approximately 600 atoms (mineralized). Structures were also obtained BfrB after they had soaked in an FeSO(4) solution (Fe soak) separate experiments followed by a soak crystallization (double soak). Although the structures consist typical fold comprised nearly spherical 24-mer assembly that binds 12 heme...

The extreme limitation of free iron has driven various pathogens to acquire from the host in form heme. Specifically, several Gram-negative secrete a heme binding protein known as HasA scavenge extracellular environment and transfer it receptor HasR for import into bacterial cell. Structures heme-bound apo-HasA homologues show that iron(III) ligands, His32 Tyr75, reside on loops extending core significant conformational change must occur at loop upon binding. Here, we investigate kinetics...

When challenged by low-iron conditions several Gram-negative pathogens secrete a hemophore (HasA) to scavenge hemin from its host and deliver it receptor (HasR) on their outer membrane for internalization. Here we report results studies aimed at probing the structural dynamic processes play in loading of apo-hemophore secreted P. aeruginosa (apo-HasAp) with hemin. The structure apo-HasAp shows large conformational change loop harboring axial ligand His32 relative holo-HasAp, whereas bearing...

Iron is an essential nutrient for bacteria but the reactivity of Fe2+ and insolubility Fe3+ present significant challenges to bacterial cells. storage proteins contribute ameliorating these by oxidizing using O2 H2O2 as electron acceptors, compartmentalizing Fe3+. Two types iron-storage coexist in bacteria, ferritins (Ftn) heme-containing bacterioferritins (Bfr), reasons their coexistence are largely unknown. P. aeruginosa cells harbor two iron (FtnA BfrB), nothing known about relative...

The origin of the unusual regioselectivity heme oxygenation, i.e. oxidation to δ-biliverdin (70%) and β-biliverdin (30%), that is exhibited by oxygenase from Pseudomonas aeruginosa (pa-HO) has been studied 1H NMR, 13C resonance Raman spectroscopies. Whereas indicates heme−iron ligation in pa-HO homologous observed previously α-hydroxylating oxygenases, NMR spectroscopic studies suggest this enzyme seated a manner distinct for all other enzymes which structure known. In pa-HO, rotated...

The 13C pulsed ENDOR and NMR study of [meso-13C-TPPFe(OCH3)(OOtBu)]- performed in this work shows that although the unpaired electron low-spin ferrihemes containing a ROO- ligand resides dπ orbital at 8 K, dxy configuration is favored physiological temperatures. variable temperature spectra indicate dynamic situation which heme with planar porphyrinate ring equilibrium has ruffled porphyrin ring. Because similarity EPR hydroperoxide complexes oxygenase, cytochrome P450, model complex...

Pseudomonas aeruginosa secretes a 205 residue long hemophore (full-length HasAp) that is subsequently cleaved at the C′-terminal domain to produce mainly 184 truncated HasAp scavenges heme [Letoffé, S., Redeker, V., and Wandersman, C. (1998) Mol. Microbiol. 28, 1223−1234]. has been characterized by X-ray crystallography in solution NMR spectroscopy. The crystal structure of revealed polypeptide αβ fold ferriheme coordinated axially His32 Tyr75, with side chain His83 poised accept hydrogen...

Two distinct types of ferritin-like molecules often coexist in bacteria, the heme binding bacterioferritins (Bfr) and non-heme bacterial ferritins (Ftn). The early isolation a molecule from Pseudomonas aeruginosa suggested possibility bacterioferritin assembled two different subunits [Moore, G. R., et al. (1994) Biochem. J. 304, 493-497]. Subsequent studies demonstrated presence genes encoding P. aeruginosa, designated bfrA bfrB, that may [Ma, J.-F., (1999) Bacteriol. 181, 3730-3742]. In...

Although iron is essential for bacteria, the nutrient presents problems of toxicity and solubility. Bacteria circumvent these with aid storage proteins where Fe3+ deposited and, when necessary, mobilized as Fe2+ metabolic requirements. In Pseudomonas aeruginosa, compartmentalized in bacterioferritin (BfrB), its mobilization requires specific binding a ferredoxin (Bfd) to reduce stored Fe3+. Blocking BfrB-Bfd complex leads irreversible accumulation BfrB cytosolic deprivation. Consequently,...

Ferritins are iron storage proteins assembled from 24 subunits into a spherical and hollow structure. The genomes of many bacteria harbor genes encoding two types ferritin-like proteins, the bacterial ferritins (Ftn) bacterioferritins (Bfr), which bind heme. genome P. aeruginosa PAO1 (like bacteria) contains coding for different molecules, ftnA (PA4235) bfrB (PA3531). reasons requiring presence distinct protein in cells have remained largely unexplained. Attempts to understand this issue...

When the reduction potential of cytochrome b5 is measured with aid several different surface-modified electrodes that function on basis electrostatic interactions protein, resultant values have been consistently more positive (40−100 mV) than potentials potentiometric methods. In this paper, we report heme edge containing exposed propionate, a methyl, and vinyl, which constitutes part surface b5, modulates its potential. The shifts observed in voltammetric measurements appear to originate...

The role played by the outer mitochondrial membrane (OM) cytochrome b5 heme propionate groups in electrostatic binding between OM and horse heart c was investigated 13C NMR spectroscopy X-ray crystallography. To achieve these aims, 13C-labeled expressed Escherichia coli as previously described [Rivera M., Walker, F.A. (1995) Anal. Biochem. 230, 295-302]. Assignment of resonances arising from carbons ferricytochrome carried out a combination one- two-dimensional experiments. Titrations...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTGene synthesis, bacterial expression and proton NMR spectroscopic studies of the rat outer mitochondrial membrane cytochrome b5Mario Rivera, Carolina Barillas-Mury, Kenner A. Christensen, John W. Little, Michael Wells, F. Ann WalkerCite this: Biochemistry 1992, 31, 48, 12233–12240Publication Date (Print):December 8, 1992Publication History Published online1 May 2002Published inissue 8 December...

Hemophores from Serratia marcescens (HasA(sm)) and Pseudomonas aeruginosa (HasA(p)) bind hemin between two loops, which harbor the axial ligands H32 Y75. Hemin binding to Y75 loop triggers closing of enables H32. Because Yersinia pestis HasA (HasA(yp)) presents a Gln at position 32, we determined structures apo- holo-HasA(yp). Surprisingly, Q32 in apo-HasA(yp) is already closed conformation, but no residue binds In agreement with minimal reorganization holo-structures, on-rate too fast...

Burkholderia pseudomallei, the causative agent of melioidosis, encodes almost a dozen predicted polyketide (PK) biosynthetic gene clusters. Many these are regulated by LuxR-I-type acyl-homoserine (AHL) quorum-sensing systems. One PK clusters, mal cluster, is conserved in close relative thailandensis The B. genes code for cytotoxin malleilactone and genetically linked LuxR-type transcription factor, MalR. Although AHLs typically interact with proteins to modulate transcription, MalR does not...