Bacterioferritin Comigratory Protein Research Articles

Kinetic characterization of a BCP‐class peroxiredoxin from Escherichia coli

Peroxiredoxins (Prx) possess a conserved active site structure centered around the catalytic residue (the “peroxidatic” cysteine) which forms a cysteine sulfenic acid upon reaction with peroxides. This cysteine subsequently forms a disulfide bond with a resolving cysteine (either inter‐ or intramolecular) and/or the reductant during reductive recycling. In Escherichia coli, bacterioferritin‐comigratory protein (BCP) is a peroxiredoxin which catalyzes the reduction of hydrogen peroxide and alkyl hydroperoxides. BCP exhibits a broad specificity for reductants and peroxide substrates, potentially allowing BCP to remain fully active and functional under varying cellular conditions. BCP demonstrated comparable peroxidase activity when acting upon H2O2 and cumene hydroperoxide. During thioredoxin‐dependent peroxidase activity studies conducted by stopped flow spectroscopy, a linear rate increase was observed with increasing reducing substrate along with a turnover rate ~44 times faster than those previously reported. In our studies, BCP exhibited a kcat of 1.31 s−1 and a kcat/Km (for H2O2) of 1.42 x 104 M−1 s−1 using 10 μM thioredoxin as reductant. An exploration of other potential reductants of BCP revealed that Grx1 and Trx2 also act as reductants of BCP in E. coli. However, kcat/Km of BCP for H2O2 when utilizing Trx as an electron donor was calculated to be 2x and 11x higher than those demonstrated by Grx1 and Trx2 respectively. Supported by NIH RO1 GM50389 to LBP.

Distinct functional roles of peroxiredoxin isozymes and glutathione peroxidase from fission yeast, Schizosaccharomyces pombe

To investigate the differences in the functional roles of peroxiredoxins (Prxs) and glutathione peroxidase (GPx) of Schizosaccharomyces pombe, we examined the peroxidase and molecular chaperone properties of the recombinant proteins. TPx (thioredoxin peroxidase) exhibited a capacity for peroxide reduction with the thioredoxin system. GPx also showed thioreoxin-dependent peroxidase activity rather than GPx activity. The peroxidase activity of BCP (bacterioferritin comigratory protein) was similar to that of TPx. However, peroxidase activity was not observed for PMP20 (peroxisomal membrane protein 20). TPx, PMP20, and GPx inhibited thermal aggregation of citrate synthase at 43(o)C, but BCP failed to inhibit the aggregation. The chaperone activities of PMP20 and GPx were weaker than that of TPx. The peroxidase and chaperone properties of TPx, BCP, and GPx of the fission yeast are similar to those of Saccharomyces cerevisiae. The fission yeast PMP20 without thioredoxin-dependent peroxidase activity may act as a molecular chaperone.

Subdivision of the Bacterioferritin Comigratory Protein Family of Bacterial Peroxiredoxins Based on Catalytic Activity

Peroxiredoxins are ubiquitous proteins that catalyze the reduction of hydroperoxides, thus conferring resistance to oxidative stress. Using high-resolution mass spectrometry, we recently reclassified one such peroxiredoxin, bacterioferritin comigratory protein (BCP) of Escherichia coli, as an atypical 2-Cys peroxiredoxin that functions through the formation of an intramolecular disulfide bond between the active and resolving cysteine. An engineered E. coli BCP, which lacked the resolving cysteine, retained enzyme activity through a novel catalytic pathway. Unlike the active cysteine, the resolving cysteine of BCP peroxiredoxins is not conserved across all members of the family. To clarify the catalytic mechanism of native BCP enzymes that lack the resolving cysteine, we have investigated the BCP homologue of Burkholderia cenocepacia. We demonstrate that the B. cenocepacia BCP (BcBCP) homologue functions through a 1-Cys catalytic pathway. During catalysis, BcBCP can utilize thioredoxin as a reductant for the sulfenic acid intermediate. However, significantly higher peroxidase activity is observed utilizing glutathione as a resolving cysteine and glutaredoxin as a redox partner. Introduction of a resolving cysteine into BcBCP changes the activity from a 1-Cys pathway to an atypical 2-Cys pathway, analogous to the E. coli enzyme. In contrast to the native B. cenocepacia enzyme, thioredoxin is the preferred redox partner for this atypical 2-Cys variant. BCP-deficient B. cenocepacia exhibit a growth-phase-dependent hypersensitivity to oxidative killing. On the basis of sequence alignments, we believe that BcBCP described herein is representative of the major class of bacterial BCP peroxiredoxins. To our knowledge, this is the first detailed characterization of their catalytic activity. These studies support the subdivision of the BCP family of peroxiredoxins into two classes based on their catalytic activity.

Insights into the Alkyl Peroxide Reduction Pathway of Xanthomonas campestris Bacterioferritin Comigratory Protein from the Trapped Intermediate–Ligand Complex Structures

Considerable insights into the oxidoreduction activity of the Xanthomonas campestris bacterioferritin comigratory protein (XcBCP) have been obtained from trapped intermediate/ligand complex structures determined by X-ray crystallography. Multiple sequence alignment and enzyme assay indicate that XcBCP belongs to a subfamily of atypical 2-Cys peroxiredoxins (Prxs), containing a strictly conserved peroxidatic cysteine (CP48) and an unconserved resolving cysteine (CR84). Crystals at different states, i.e. Free_SH state, Intra_SS state, and Inter_SS state, were obtained by screening the XcBCP proteins from a double C48S/C84S mutant, a wild type, and a C48A mutant, respectively. A formate or an alkyl analog with two water molecules that mimic an alkyl peroxide substrate was found close to the active site of the Free_SH or Inter_SS state, respectively. Their global structures were found to contain a novel substrate-binding pocket capable of accommodating an alkyl chain of no less than 16 carbons. In addition, in the Intra_SS or Inter_SS state, substantial local unfolding or complete unfolding of the CR-helix was detected, with the CP-helix remaining essentially unchanged. This is in contrast to the earlier observation that the CP-helix exhibits local unfolding during disulfide bond formation in typical 2-Cys Prxs. These rich experimental data have enabled us to propose a pathway by which XcBCP carries out its oxidoreduction activity through the alternate opening and closing of the substrate entry channel and the disulfide-bond pocket.

Interrogating the Molecular Details of the Peroxiredoxin Activity of the Escherichia coli Bacterioferritin Comigratory Protein Using High-Resolution Mass Spectrometry

Bacterioferritin comigratory protein (BCP) is a bacterial thioredoxin-dependent thiol peroxidase that reduces a variety of peroxide substrates. Using high-resolution Fourier transform ion cyclotron resonance mass spectrometry coupled with top-down fragmentation techniques, we have analyzed the mechanistic details of hydrogen peroxide reduction by E. coli BCP. We show here that catalysis occurs via an atypical two-cysteine peroxiredoxin pathway. A transient sulfenic acid is initially formed on Cys-45, before resolution by the formation of an intramolecular disulfide bond between Cys-45 and Cys-50. This oxidized BCP intermediate is shown to be a substrate for reduction by thioredoxin, completing the catalytic cycle. Although we invoke Cys-50 in the catalytic cycle of Escherichia coli bacterioferritin comigratory protein (BCP), a previous study had shown that this residue was not absolutely required for peroxiredoxin activity. In order to explain these apparently conflicting phenomena, we analyzed the reaction of a C50S BCP mutant with peroxide. We show that this mutant BCP enzyme adopts a different and novel mechanistic pathway. The C50S BCP mutant reacts with peroxide to form a sulfenic acid on Cys-45, in the same manner as wild-type BCP. However, the nascent intermediate is then resolved by reaction with Cys-45 from a second BCP molecule, resulting in a dimeric intermediate containing an intermolecular disulfide bond. We further show that this novel resolving complex is a substrate for reduction by thioredoxin. The importance of our results in furthering the understanding of catalysis within BCP family is discussed.

Overexpression of bacterioferritin comigratory protein (Bcp) enhance viability and reduced glutathione level in the fission yeast under stress

The structural gene encoding bacterioferritin comigratory protein (Bcp) was amplified using PCR from the genomic DNA of Schizosaccharomyces pombe, and transferred into the shuttle vector pRS316 to generate the recombinant plasmid pBCPlO. The bcp(+) mRNA level in the pBCPlO-containing yeast cells was significantly higher than that in the control yeast cells, indicating that the cloned gene is functioning. The S. pombe cells harboring the plasmid pBCPIO exhibited higher survival on the solid minimal media with hydrogen peroxide, tert-BOOH or cadmium than the control yeast cells. They also exhibited enhanced cellular viability in the liquid media containing the stressful agents. The increased viabilities of the fission yeast cells harboring the plasmid pBCP10 were also obtained with 0.4% glucose or 0.4% sucrose as a sole carbon source, and nitrogen starvation, compared with those of the control yeast cells. The total glutathione (GSH) content and total GSH/GSSG ratio were significantly higher in the yeast cells harboring the plasmid pBCP10 than in the control yeast cells. In brief, the S. pombe Bcp plays a protective role in the defensive response to oxidative stress possibly via up-regulation of total and reduced glutathione levels.

ASSOCIATION OF HELICOBACTER PYLORI SEROPOSITIVITY WITH CORONARY ARTERY DISEASE

Oxidative stress conditions lead to enzymatic and non-enzymatic unsaturated fatty acid-initiated lipid peroxidation reactions. One exacerbating product is lipid hydroperoxide (LOOH) which itself promotes formation of several additional peroxyl radicals. Helicobacter pylori mutant strains with disruptions in genes encoding the peroxiredoxins, alkyl hydroperoxide reductase (ahpC) and the bacterioferritin comigratory protein (bcp), were more sensitive than the parent strain to oxidizing agents. These mutant strains were particularly sensitive, compared to the wild type, to killing by the unsaturated fatty acid linolenic acid but were not sensitive to the saturated fatty acid palmitic acid. A double mutant strain (ahpC bcp) accumulated more than 3-fold more lipid peroxides than the parent strain, indicating these peroxiredoxins together play a role in detoxifying lipid peroxides. The level of free iron accumulation, a signature of oxidative stress damage, was correlated specifically to organic peroxide-mediated stress by both in vivo and in vitro approaches. Free iron accumulation and concomitant destruction of [Fe–S] cluster-containing proteins (hydrogenase and aconitase) was correlated to damage mediated by exogenous t-butyl peroxide, or separately to intracellular accumulation of lipid peroxides in mutant strains. A major macromolecular target of accumulating lipid peroxides in H. pylori is DNA, as mutant analysis approaches combined with quantitative DNA fragmentation studies and specific DNA damage assessment (i.e. 8-oxoguanine formation) were used to demonstrate that such damage was especially associated with ahpC and ahpC bcp strains.

Peroxiredoxins as cellular guardians in Sulfolobus solfataricus– characterization of Bcp1, Bcp3 and Bcp4

Peroxiredoxins are ubiquitous enzymes that are part of the oxidative stress defense system. In the present study, we identified three peroxiredoxins [bacterioferritin comigratory protein (Bcp)1, Bcp3 and Bcp4] in the genome of the aerobic hyperthermophilic archaeon Sulfolobus solfataricus. Based on the cysteine residues conserved in the deduced aminoacidic sequence, Bcp1 and Bcp4 can be classified as 2-Cys peroxiredoxins and Bcp3 as a 1-Cys peroxiredoxin. A comparative study of the recombinant Bcps produced in Escherichia coli showed that these enzymes protect DNA plasmid from oxidative damage and remove both H(2)O(2) and tert-butyl hydroperoxide, although at different efficiencies. We observed that all of them were particularly thermostable and that peak enzymatic activity fell within the range of the growth temperature of S. solfataricus. Furthermore, we discovered an alternative Bcp reduction system whose composition differs from that of the peroxiredoxin reduction system previously characterized in the aerobic hyperthermophilic archaeon Aeropyrum pernix. Whereas the latter uses the thioredoxin/thioredoxin reductase/NADPH system, this alternative Bcp system is formed of the protein disulfide oxidoreducatase, SSO0192, the thioredoxin reductase, SSO2416, and NADPH. The role of Bcps in oxidative stress was investigated using transcriptional analysis. Different northern blot analysis responses suggested that the Bcp antioxidant system of S. solfataricus can both operate at the constitutive level, with Bcp1 and Bcp4 preventing endogenous peroxide formation, and at the inducible level, with Bcp3 and the already characterized Bcp2 protecting cells from the attack of external peroxides.

Four thiol peroxidases contain a conserved GCT catalytic motif and act as a versatile array of lipid peroxidases in Anabaena sp. PCC7120

The Anabaena sp. (ANASP) genome contains seven open reading frames with homology to thiol peroxidase (TPx), also known as peroxiredoxin (Prx). Based on sequence similarities among putative TPxs derived from various cyanobacteria genomes, we designated the seven putative TPx members as VCP, VCT, TCS, and GCT cluster according to the sequence of their conserved catalytic motif. The GCT cluster consists of four members, named GCT1, GCT2, GCT3, and GCT4. The ANASP GCT-TPx genes were recombinantly expressed in Escherichia coli. The purified proteins were characterized with an emphasis on the capability to destroy various peroxides, the electron donor, and the conserved cysteine structure as a catalytic intermediate. All GCT members, as an atypical 2-Cys TPx family, exerted the highest peroxidase activity toward a lipid hydroperoxide using an electron from thioredoxin. Periplasmic protein analysis revealed that GCT2 and GCT4 are distributed in the cytoplasm, whereas GCT1 and GCT3, homologues of Escherichia coli bacterioferritin co-migratory protein (BCP)/plant PrxQ, are localized in the periplasmic space. Immunoblots of the heterocystic proteins showed that the level of GCT2 in the heterocyst is comparable to that in the vegetative cell, while the other GCT members were not significantly detected in the heterocyst. The transcriptional responses of ANASP GCT genes to various oxidative stresses and growth environments were multifarious. Their intrinsic differences in transcriptional responsiveness and cellular localization suggest that this large GCT cluster is designed as an adaptive strategy to efficiently combat lipid hydroperoxide in Anabaena sp. that perform oxygenic photosynthesis and N2-fixation.

The diverse antioxidant systems of Helicobacter pylori

The gastric pathogen Helicobacter pylori induces a strong inflammatory host response, yet the bacterium maintains long-term persistence in the host. H. pylori combats oxidative stress via a battery of diverse activities, some of which are unique or newly described. In addition to using the well-studied bacterial oxidative stress resistance enzymes superoxide dismutase and catalase, H. pylori depends on a family of peroxiredoxins (alkylhydroperoxide reductase, bacterioferritin co-migratory protein and a thiol-peroxidase) that function to detoxify organic peroxides. Newly described antioxidant proteins include a soluble NADPH quinone reductase (MdaB) and an iron sequestering protein (NapA) that has dual roles - host inflammation stimulation and minimizing reactive oxygen species production within H. pylori. An H. pylori arginase attenuates host inflammation, a thioredoxin required as a reductant for many oxidative stress enzymes is also a chaperon, and some novel properties of KatA and AhpC were discovered. To repair oxidative DNA damage, H. pylori uses an endonuclease (Nth), DNA recombination pathways and a newly described type of bacterial MutS2 that specifically recognizes 8-oxoguanine. A methionine sulphoxide reductase (Msr) plays a role in reducing the overall oxidized protein content of the cell, although it specifically targets oxidized Met residues. H. pylori possess few stress regulator proteins, but the key roles of a ferric uptake regulator (Fur) and a post-transcriptional regulator CsrA in antioxidant protein expression are described. The roles of all of these antioxidant systems have been addressed by a targeted mutant analysis approach and almost all are shown to be important in host colonization. The described antioxidant systems in H. pylori are expected to be relevant to many bacterial-associated diseases, as genes for most of the enzymes carrying out the newly described roles are present in a number of pathogenic bacteria.

Lipid peroxidation as a source of oxidative damage in Helicobacter pylori: Protective roles of peroxiredoxins

Oxidative stress conditions lead to enzymatic and non-enzymatic unsaturated fatty acid-initiated lipid peroxidation reactions. One exacerbating product is lipid hydroperoxide (LOOH) which itself promotes formation of several additional peroxyl radicals. Helicobacter pylori mutant strains with disruptions in genes encoding the peroxiredoxins, alkyl hydroperoxide reductase ( ahpC) and the bacterioferritin comigratory protein ( bcp), were more sensitive than the parent strain to oxidizing agents. These mutant strains were particularly sensitive, compared to the wild type, to killing by the unsaturated fatty acid linolenic acid but were not sensitive to the saturated fatty acid palmitic acid. A double mutant strain ( ahpC bcp) accumulated more than 3-fold more lipid peroxides than the parent strain, indicating these peroxiredoxins together play a role in detoxifying lipid peroxides. The level of free iron accumulation, a signature of oxidative stress damage, was correlated specifically to organic peroxide-mediated stress by both in vivo and in vitro approaches. Free iron accumulation and concomitant destruction of [Fe–S] cluster-containing proteins (hydrogenase and aconitase) was correlated to damage mediated by exogenous t-butyl peroxide, or separately to intracellular accumulation of lipid peroxides in mutant strains. A major macromolecular target of accumulating lipid peroxides in H. pylori is DNA, as mutant analysis approaches combined with quantitative DNA fragmentation studies and specific DNA damage assessment (i.e. 8-oxoguanine formation) were used to demonstrate that such damage was especially associated with ahpC and ahpC bcp strains.

Contribution of the Helicobacter pylori Thiol Peroxidase Bacterioferritin Comigratory Protein to Oxidative Stress Resistance and Host Colonization

Peroxiredoxins, the enzymes that catalyze the reduction of hydrogen peroxide and organic hydroperoxides, are ubiquitous proteins that protect organisms from damage by reactive oxygen species. Helicobacter pylori contains three members of the peroxiredoxin family: AhpC (alkyl hydroperoxide reductase), Tpx (thiol-specific peroxidase), and bacterioferritin comigratory protein (BCP). In this study, we characterized H. pylori bcp mutant strains and wild-type BCP. Compared to the parent strain and the ahpC mutant strain, the bcp mutant showed moderate sensitivity to the superoxide-generating agent paraquat and to organic hydroperoxides. Upon exposure of 10(8) cells to air for 10 h, 10(6) wild-type cells survived but none of the 10(8) bcp mutant cells were recovered. Introduction of an intact bcp gene at an unrelated locus in the bcp strain restored the wild-type-like oxidative stress resistance phenotype. Purified BCP was shown to be a thiol peroxidase that depends on the reducing activity of thioredoxin and thioredoxin reductase. Among a series of peroxides tested, linoleic acid hydroperoxide was the preferred substrate of BCP. By examining the profiles of protein expression within H. pylori cells, we confirmed that AhpC is much more abundant than BCP. The overlapping functions and activities of BCP and AhpC probably explain why the bcp mutant displayed a relatively weak oxidative stress resistance phenotype. The bcp mutant strain could colonize mouse stomachs, although colonization by the wild-type strain was slightly better than that by the mutant strain at 1 week after host inoculation. However, at 3 weeks after inoculation, the colonization ability of the wild type was significantly greater than that of the bcp mutant; for example, H. pylori was recovered from 10 of 11 mouse stomachs inoculated with the wild-type strain but from only 4 of 12 mice that were inoculated with the bcp mutant strain. This indicates that H. pylori BCP plays a significant role in efficient host colonization.

Modification of the protein expression pattern induced in the nitrogen-fixing actinomycete Frankia sp. strain ACN14a-tsr by root exudates of its symbiotic host Alnus glutinosa and cloning of the sodF gene.

Two-dimensional (2-D) polyacrylamide gel electrophoresis was used to detect proteins induced in Frankia sp. strain ACN14a-tsr by root exudates of its symbiotic host, Alnus glutinosa. The 5 most prominent proteins were purified from 2-D gels and characterized by N-terminal sequencing. All of these proteins had a high percentage of similarity with known stress proteins. One protein match was the Fe superoxide dismutase (Fe-SOD), another was a tellurite resistance protein (Ter), the third was a bacterioferritin comigratory protein (Bcp); and two matches, differing only by their isoelectric point, were the same small heat shock protein (Hsp), a major immune reactive protein found in mycobacteria. This suggests that the symbiotic microorganism Frankia, first responds with a normal stress response to toxic root products of its symbiotic host plant. To confirm its identity, the gene corresponding to the Fe-SOD protein, sodF was isolated from a genomic library by a PCR-approach and sequenced. It is the first stress response gene characterized in Frankia.

PerR controls oxidative stress resistance and iron storage proteins and is required for virulence in Staphylococcus aureus.

The Staphylococcus aureus genome encodes three ferric uptake regulator (Fur) homologues: Fur, PerR, and Zur. To determine the exact role of PerR, we inactivated the gene by allelic replacement using a kanamycin cassette, creating strain MJH001 (perR). PerR was found to control transcription of the genes encoding the oxidative stress resistance proteins catalase (KatA), alkyl hydroperoxide reductase (AhpCF), bacterioferritin comigratory protein (Bcp), and thioredoxin reductase (TrxB). Furthermore, PerR regulates transcription of the genes encoding the iron storage proteins ferritin (Ftn) and the ferritin-like Dps homologue, MrgA. Transcription of perR was autoregulated, and PerR repressed transcription of the iron homeostasis regulator Fur, which is a positive regulator of catalase expression. PerR functions as a manganese-dependent, transcriptional repressor of the identified regulon. Elevated iron concentrations produced induction of the PerR regulon. PerR may act as a peroxide sensor, since addition of external hydrogen peroxide to 8325-4 (wild type) resulted in increased transcription of most of the PerR regulon, except for fur and perR itself. The PerR-regulated katA gene encodes the sole catalase of S. aureus, which is an important starvation survival determinant but is surprisingly not required for pathogenicity in a murine skin abscess model of infection. In contrast, PerR is not necessary for starvation survival but is required for full virulence (P < 0.005) in this model of infection. PerR of S. aureus may act as a redox sentinel protein during infection, analogous to the in vitro activities of OxyR and PerR of Escherichia coli and Bacillus subtilis, respectively. However, it differs in its response to the metal balance within the cell and has the added capability of regulating iron uptake and storage.

A novel peroxiredoxin of the plant Sedum lineare is a homologue of Escherichia coli bacterioferritin co-migratory protein (Bcp).

We cloned a gene encoding a 17-kDa protein from a cDNA library of the plant Sedum lineare and found that its deduced amino acid sequence showed similarities to those of Escherichia coli bacterioferritin co-migratory protein (Bcp) and its homologues, which comprise a discrete group associated with the peroxiredoxin (Prx) family. Studies of the recombinant 17-kDa protein produced in E. coli cells revealed that it actually had a thioredoxin-dependent peroxidase activity, the hallmark of the Prx family. PrxQ, as we now designate the 17-kDa protein, had two cysteine residues (Cys-44 and Cys-49) well conserved among proteins of the Bcp group. These two cysteines were demonstrated to be essential for the thioredoxin-dependent peroxidase activity by analysis of mutant proteins, suggesting that these residues are involved in the formation of an intramolecular disulphide bond as an intermediate in the reaction cycle. Expression of PrxQ suppressed the hypersensitivity of an E. coli bcp mutant to peroxides, indicating that it might exert an antioxidant activity in vivo.

A novel peroxiredoxin of the plant Sedum lineare is a homologue of Escherichia coli bacterioferritin co-migratory protein (Bcp)

We cloned a gene encoding a 17-kDa protein from a cDNA library of the plant Sedum lineare and found that its deduced amino acid sequence showed similarities to those of Escherichia coli bacterioferritin co-migratory protein (Bcp) and its homologues, which comprise a discrete group associated with the peroxiredoxin (Prx) family. Studies of the recombinant 17-kDa protein produced in E. coli cells revealed that it actually had a thioredoxin-dependent peroxidase activity, the hallmark of the Prx family. PrxQ, as we now designate the 17-kDa protein, had two cysteine residues (Cys-44 and Cys-49) well conserved among proteins of the Bcp group. These two cysteines were demonstrated to be essential for the thioredoxin-dependent peroxidase activity by analysis of mutant proteins, suggesting that these residues are involved in the formation of an intramolecular disulphide bond as an intermediate in the reaction cycle. Expression of PrxQ suppressed the hypersensitivity of an E. coli bcp mutant to peroxides, indicating that it might exert an antioxidant activity in vivo. The sequence data presented have been deposited in the GenBank/EMBL/DDBJ nucleotide sequence databases under the accession number AB037598.

Thioredoxin-dependent Hydroperoxide Peroxidase Activity of Bacterioferritin Comigratory Protein (BCP) as a New Member of the Thiol-specific Antioxidant Protein (TSA)/Alkyl Hydroperoxide Peroxidase C (AhpC) Family

Escherichia coli bacterioferritin comigratory protein (BCP), a putative bacterial member of the TSA/AhpC family, was characterized as a thiol peroxidase. BCP showed a thioredoxin-dependent thiol peroxidase activity. BCP preferentially reduced linoleic acid hydroperoxide rather than H(2)O(2) and t-butyl hydroperoxide with the use of thioredoxin as an in vivo immediate electron donor. The value of V(max)/K(m) of BCP for linoleic acid hydroperoxide was calculated to be 5-fold higher than that for H(2)O(2), implying that BCP has a selective capability to reduce linoleic acid hydroperoxide. Replacement of Cys-45 with serine resulted in the complete loss of thiol peroxidase activity, suggesting that BCP is a new bacterial member of TSA/AhpC family having a conserved cysteine as the primary site of catalysis. BCP exists as a monomer, and its functional Cys-45 appeared to exist as cysteine sulfenic acid. The expression level of BCP gradually elevated during exponential growth until mid-log phase growth, beyond which the expression level was decreased. BCP was induced 3-fold by the oxidative stress given by changing the growth conditions from the anaerobic to aerobic culture. Bcp null mutant grew more slowly than its wild type in aerobic culture and showed the hypersensitivity toward various oxidants such as H(2)O(2), t-butyl hydroperoxide, and linoleic acid hydroperoxide. The peroxide hypersensitivity of the null mutant could be complemented by the expression of bcp gene. Taken together, these data suggest that BCP is a new member of thioredoxin-dependent TSA/AhpC family, acting as a general hydroperoxide peroxidase.

Nickel-induced oligomerization of proteins containing 10-histidine tags.

BioTechniquesVol. 25, No. 1 BenchmarksOpen AccessNickel-Induced Oligomerization of Proteins Containing 10-Histidine TagsTara Sprules, Nancy Green, Mark Featherstone & Kalle GehringTara Sprules*Address correspondence to Ms. Tara Sprules, Department of Biochemistry, McIntyre Medical Science Building, McGill University, 3655 Drummond, Montreal, QC H3G 1Y6, Canada. Internet: E-mail Address: tara@bri.nrc.caMcGill University, Montreal, QC, CanadaSearch for more papers by this author, Nancy GreenMcGill University, Montreal, QC, CanadaSearch for more papers by this author, Mark FeatherstoneMcGill University, Montreal, QC, CanadaSearch for more papers by this author & Kalle GehringMcGill University, Montreal, QC, CanadaSearch for more papers by this authorPublished Online:15 Aug 2018https://doi.org/10.2144/98251bm02AboutSectionsPDF/EPUB ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinkedInRedditEmail "Nickel-Induced Oligomerization of Proteins Containing 10-Histidine Tags." , 25(1), pp. 20–22FiguresReferencesRelatedDetailsCited ByS100 proteins as therapeutic targets31 October 2018 | Biophysical Reviews, Vol. 10, No. 6His-Tag-Mediated Dimerization of Chemoreceptors Leads to Assembly of Functional Nanoarrays5 September 2017 | Biochemistry, Vol. 56, No. 44Characterization of a bacterioferritin comigratory protein family 1-Cys peroxiredoxin from Candidatus Liberibacter asiaticus16 December 2016 | Protoplasma, Vol. 254, No. 4Assembly and Molecular Architecture of the Phosphoinositide 3-Kinase p85α HomodimerJournal of Biological Chemistry, Vol. 290, No. 51Impact of PNKP mutations associated with microcephaly, seizures and developmental delay on enzyme activity and DNA strand break repair14 April 2012 | Nucleic Acids Research, Vol. 40, No. 14Zinc-phosphate nanoparticles with reversibly attached TNF-α analogs: an interesting concept for potential use in active immunotherapy11 January 2011 | Journal of Nanoparticle Research, Vol. 13, No. 7His-tags as Zn(II) binding motifs in a protein-based fluorescent sensor13 May 2008 | Protein Engineering Design and Selection, Vol. 21, No. 8Dynamics of Membrane Protein/Amphipol Association Studied by Förster Resonance Energy Transfer: Implications for in Vitro Studies of Amphipol-Stabilized Membrane Proteins18 August 2007 | Biochemistry, Vol. 46, No. 36Purification of VP3 protein of infectious bursal disease virus using nickel ion-immobilized regenerated cellulose-based membranesJournal of Chromatography B, Vol. 840, No. 2Site-Specific Cross-Linking of Proteins through Tyrosine Hexahistidine Tags1 November 2005 | Bioconjugate Chemistry, Vol. 16, No. 6The screening of expression and purification conditions for replicative DNA polymerase associated B-subunits, assignment of the exonuclease activity to the C-terminus of archaeal pol D DP1 subunitProtein Expression and Purification, Vol. 43, No. 1Cysteine mediated multimerization of a recombinant dengue E fragment fused to the P64k protein following immobilized metal ion affinity chromatographyProtein Expression and Purification, Vol. 34, No. 2Characterization of His-tagged, R6K-encoded π protein variantsPlasmid, Vol. 50, No. 1Current and prospective applications of metal ion–protein bindingJournal of Chromatography A, Vol. 988, No. 1Negative Purification Method for the Selection of Specific Antibodies from Polyclonal AntiseraCindy Benet & Pierre Van Cutsem17 September 2018 | BioTechniques, Vol. 33, No. 5Recombinant PhycobiliproteinsAnalytical Biochemistry, Vol. 290, No. 2Monomer/Dimer ratios of replication protein modulate the DNA strand-opening in a replication originJournal of Molecular Biology, Vol. 306, No. 5Autophosphorylation of the Insulin-like Growth Factor I Receptor Cytoplasmic DomainBiochemical and Biophysical Research Communications, Vol. 279, No. 3Purification of Overexpressed Hexahistidine-Tagged BLM N431 as Oligomeric ComplexesProtein Expression and Purification, Vol. 17, No. 2 Vol. 25, No. 1 Follow us on social media for the latest updates Metrics Downloaded 267 times History Published online 15 August 2018 Published in print July 1998 Information© 2018 Author(s)PDF download

The fimA locus of Streptococcus parasanguis encodes an ATP-binding membrane transport system.

The gene encoding fimA, a 36 kDa fimbrial adhesion of Streptococcus parasanguis FW213, is highly conserved in all four genetic groups of sanguis streptococci. FimA-like peptides were produced by all strains tested. The nucleotide sequence directly upstream of fimA contains two open reading frames, ORF5 and ORF1, whose deduced protein products are homologous to members of a superfamily of ATP-binding cassette membrane transport proteins, including both prokaryotic and eukaryotic uptake and export systems. The amino acid sequence of FimA contains the consensus prolipoprotein cleavage site (LxxC) common to the 'periplasmic' binding proteins of Gram-positive transport systems. The deduced product of ORF5 is a 28.6 kDa membrane-associated protein that has the consensus binding site for ATP (GxxGxGKS). It shares significant homology with AmiE of Streptococcus pneumoniae as well as with Escherichia coli proteins involved in iron(III) uptake. Allelic-replacement mutagenesis of ORF5 resulted in greatly increased resistance to aminopterin. These data demonstrate functionality with the amiE locus as well. The deduced product of ORF1 is an extremely hydrophobic integral membrane protein of 30.8 kDa with a pattern of six potential membrane-spanning regions, typical of a component of these types of transport system. The nucleotide sequence downstream of fimA, ORF3, encodes a 20 kDa protein having 78% identity with the 20 kDa protein encoded downstream of ssaB, a fimA homologue in S. sanguis 12. It also exhibits significant homology with bacterioferritin co-migratory protein (Bcp) of E. coli K-12. Allelic-replacement mutagenesis in the fimA locus of FW213 showed that (i) expression of fimA was initiated at a site far upstream of the fimA start codon, and (ii) expression of fimA was not linked to expression of ORF3. Northern blots probed with internal fragments of ORF5, ORF1, fimA or ORF3 hybridized to the same transcript of 3.3 kb, which suggested that these loci were transcribed as a polycistronic message. The ORF3 probe also hybridized to a 540 bp transcript consistent with the size of ORF3 alone and supportive of the mutagenesis data of non-linkage. Strains mutated in fimA continued to produce fimbriae, indicating that FimA was not the fimbrial structural subunit. Immunoelectron microscopy revealed FimA was localized at the tips of the fimbriae of FW213. This is the first study that demonstrates that an adhesin which binds a bacterial cell to a substrate is associated with an ATP-binding cassette.

A molecular analysis of the 53.3 minute region of the Escherichia coli linkage map

The coding characteristics of four plasmids expressing a protein (BCP) which comigrates with bacterioferritin were examined and the nucleotide sequence of a common 1985 bp segment from the 53 min region of the Escherichia coli linkage map was determined. Three open reading-frames (orf1, orf2 and orf3) were detected, and orf2 (bcp, 156 amino acid codons) appeared to encode the bacterioferritin comigratory protein, BCP. The translation product of orf3 (205 amino acid codons) resembled the iron-sulphur protein component (DMS B subunit) of the anaerobic dimethylsulphoxide reductase complex of E. coli.