| 1. |
- Baureder, Michael, et al.
(författare)
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Contribution of catalase to hydrogen peroxide resistance in Enterococcus faecalis.
- 2012
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Ingår i: FEMS Microbiology Letters. - : Oxford University Press (OUP). - 1574-6968 .- 0378-1097. ; 331:2, s. 160-164
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Enterococcus faecalis exhibits high resistance to oxidative stress. Several enzymes are responsible for this trait. The role of alkyl hydroperoxide reductase (Ahp), thiol peroxidase (Tpx), and NADH peroxidase (Npr) in oxidative stress defense was recently characterized. Enterococcus faecalis, in contrast to many other streptococci, contains a catalase (KatA), but this enzyme can only be formed when the bacterium is supplied with heme. We have used this heme dependency of catalase activity and mutants deficient in KatA and Npr to investigate the role of the catalase in resistance against exogenous and endogenous hydrogen peroxide stress. The results demonstrate that in the presence of environmental heme catalase contributes to the protection against toxic effects of hydrogen peroxide.
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| 2. |
- Baureder, Michael, et al.
(författare)
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Genes Important for Catalase Activity in Enterococcus faecalis.
- 2012
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 7:5
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Tidskriftsartikel (refereegranskat)abstract
- Little in general is known about how heme proteins are assembled from their constituents in cells. The Gram-positive bacterium Enterococcus faecalis cannot synthesize heme and does not depend on it for growth. However, when supplied with heme in the growth medium the cells can synthesize two heme proteins; catalase (KatA) and cytochrome bd (CydAB). To identify novel factors important for catalase biogenesis libraries of E. faecalis gene insertion mutants were generated using two different types of transposons. The libraries of mutants were screened for clones deficient in catalase activity using a colony zymogram staining procedure. Analysis of obtained clones identified, in addition to katA (encoding the catalase enzyme protein), nine genes distributed over five different chromosomal loci. No factors with a dedicated essential role in catalase biogenesis or heme trafficking were revealed, but the results indicate the RNA degradosome (srmB, rnjA), an ABC-type oligopeptide transporter (oppBC), a two-component signal transducer (etaR), and NADH peroxidase (npr) as being important for expression of catalase activity in E. faecalis. It is demonstrated that catalase biogenesis in E. faecalis is independent of the CydABCD proteins and that a conserved proline residue in the N-terminal region of KatA is important for catalase assembly.
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| 3. |
- Baureder, Michael, et al.
(författare)
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Heme proteins in lactic Acid bacteria.
- 2013
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Ingår i: Advances in Microbial Physiology. - 2162-5468. ; 62:1, s. 1-43
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Forskningsöversikt (refereegranskat)abstract
- Lactic acid bacteria (LAB) are of profound importance in food production and infection medicine. LAB do not rely on heme (protoheme IX) for growth and are unable to synthesize this cofactor but are generally able to assemble a small repertoire of heme-containing proteins if heme is provided from an exogenous source. These features are in contrast to other bacteria, which synthesize their heme or depend on heme for growth. We here present the cellular function of heme proteins so far identified in LAB and discuss their biogenesis as well as applications of the extraordinary heme physiology of LAB.
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| 4. |
- Baureder, Michael, et al.
(författare)
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In Vitro Assembly of Catalase.
- 2014
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Ingår i: Journal of Biological Chemistry. - 1083-351X. ; 289:41, s. 28411-28420
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Tidskriftsartikel (refereegranskat)abstract
- Most aerobic organisms contain catalase which functions to decompose hydrogen peroxide. Typical catalases are structurally complex homo-tetrameric enzymes with one heme prosthetic group buried in each subunit. It is not known how catalase in the cell is assembled from its constituents. The bacterium Enterococcus faecalis cannot synthesize heme but can acquire it from the environment to form a cytoplasmic catalase. We have in E. faecalis monitored production of the enzyme polypeptide (KatA) depending on the availability of heme and used our findings to devise a procedure for the purification of preparative amounts of in vivo-synthesized apocatalase. We show that fully active catalase can be obtained in vitro by incubating isolated apoprotein with hemin. We have characterized features of the assembly process and describe a temperature-trapped hemylated intermediate of the enzyme maturation process. Hemylation of apocatalase does not require auxiliary cell components but rapid assembly of active enzyme seemingly is assisted in the cell. Our findings provide insight about catalase assembly and offer new experimental possibilities for detailed studies of this process.
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| 5. |
- Baureder, Michael, et al.
(författare)
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Production, purification and detergent exchange of isotopically labeled Bacillus subtilis cytochrome b(558) (SdhC)
- 2011
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Ingår i: Protein Expression and Purification. - : Elsevier BV. - 1046-5928. ; 80:1, s. 97-101
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Tidskriftsartikel (refereegranskat)abstract
- Cytochrome 6558 of the gram-positive bacterium Bacillus subtilis is the membrane anchor subunit of the succinate:quinone oxidoreductase of the citric acid cycle. The cytochrome consists of the SdhC polypeptide (202 residues) and two protoheme IX groups that function in transmembrane electron transfer to menaquinone. The general structure of the cytochrome is known from extensive experimental studies and by comparison to Wolinella succinogenes fumarate reductase for which the X-ray crystal structure has been determined. Solution state NMR can potentially be used to identify the quinone binding site(s) and study, e.g. redox-linked, dynamics of cytochrome b(558). In this work we present an efficient procedure for the isolation of preparative amounts of isotopically labeled B. subtilis cytochrome 6558 produced in Escherichia coli. We have also evaluated several detergents suitable for NMR for their effectiveness in maintaining the cytochrome solubilized and intact for days at room temperature. (C) 2011 Elsevier Inc. All rights reserved.
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| 6. |
- Brugna, Myriam, et al.
(författare)
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In vivo production of catalase containing haem analogues.
- 2010
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Ingår i: The FEBS Journal. - : Wiley. - 1742-464X. ; 277:12, s. 2663-2672
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Tidskriftsartikel (refereegranskat)abstract
- Haem (protohaem IX) analogues are toxic compounds and have been considered for use as antibacterial agents, but the primary mechanism behind their toxicity has not been demonstrated. Using the haem protein catalase in the Gram-positive bacterium Enterococcus faecalis as an experimental system, we show that a variety of haem analogues can be taken up by bacterial cells and incorporated into haem-dependent enzymes. The resulting cofactor-substituted proteins are dysfunctional, generally resulting in arrested cell growth or death. This largely explains the cell toxicity of haem analogues. In contrast to many other organisms, E. faecalis does not depend on haem for growth, and therefore resists the toxicity of many haem analogues. We have exploited this feature to establish a bacterial in vivo system for the production of cofactor-substituted haem protein variants. As a pilot study, we produced, isolated and analysed novel catalase variants in which the iron atom of the haem prosthetic group is replaced by other metals, i.e. cobalt, gallium, tin, and zinc, and also variants containing meso-protoheme IX, ruthenium meso-protoporphyrin IX and (metal-free) protoporphyrin IX. Engineered haem proteins of this type are of potential use within basic research and the biotechnical industry. Structured digital abstract * MINT-7722358, MINT-7722368: katA (uniprotkb:Q834P5) and katA (uniprotkb:Q834P5) physically interact (MI:0915) by copurification (MI:0025).
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| 7. |
- Bukowska-Faniband, Ewa, et al.
(författare)
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Cortex synthesis during Bacillus subtilis sporulation depends on the transpeptidase activity of SpoVD.
- 2013
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Ingår i: FEMS Microbiology Letters. - : Oxford University Press (OUP). - 1574-6968 .- 0378-1097. ; 346:1, s. 65-72
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Tidskriftsartikel (refereegranskat)abstract
- The nonessential process of peptidoglycan synthesis during Bacillus subtilis sporulation is one model to study bacterial cell wall biogenesis. SpoVD is a class B high-molecular weight penicillin-binding protein that is specific for sporulation. Strains lacking this protein produce spores without the peptidoglycan cortex layer and are heat-sensitive. The detailed functions of the four different protein domains of the SpoVD protein are unknown and the observed phenotype of strains lacking the entire protein could be an indirect defect. We therefore inactivated the transpeptidase domain by substitution of the active site serine residue. Our results demonstrate that endospore cortex synthesis depends on the transpeptidase activity of SpoVD specifically. This article is protected by copyright. All rights reserved.
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| 8. |
- Hederstedt, Lars
(författare)
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Heme A biosynthesis
- 2012
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Ingår i: Biochimica et Biophysica Acta - Bioenergetics. - : Elsevier BV. - 0005-2728. ; 1817:6, s. 920-927
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Forskningsöversikt (refereegranskat)abstract
- Respiration in plants, most animals and many aerobic microbes is dependent on heme A. This is a highly specialized type of heme found as prosthetic group in cytochrome a-containing respiratory oxidases. Heme A differs structurally from heme B (protoheme IX) by the presence of a hydroxyethylfarnesyl group instead of a vinyl side group at the C2 position and a formyl group instead of a methyl side group at position C8 of the porphyrin macrocycle. Heme A synthase catalyzes the formation of the formyl side group and is a poorly understood heme-containing membrane bound atypical monooxygenase. This review presents our current understanding of heme A synthesis at the molecular level in mitochondria and aerobic bacteria. This article is part of a Special Issue entitled: Biogenesis/Assembly of Respiratory Enzyme Complexes. (C) 2012 Elsevier B.V. All rights reserved.
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| 9. |
- Liu, Yiming, et al.
(författare)
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Penicillin-binding protein SpoVD disulfide is a target for StoA in Bacillus subtilis forespores.
- 2010
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Ingår i: Molecular Microbiology. - : Wiley. - 1365-2958 .- 0950-382X. ; 75:1, s. 46-60
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Tidskriftsartikel (refereegranskat)abstract
- Summary The bacterial endospore is a dormant and heat-resistant form of life. StoA (SpoIVH) in Bacillus subtilis is a membrane-bound thioredoxin-like protein involved in endospore cortex synthesis. It is proposed to reduce disulfide bonds in hitherto unknown proteins in the inter-membrane compartment of developing forespores. Starting with a bioinformatic analysis combined with mutant studies we identified the sporulation-specific, high molecular weight, class B penicillin-binding protein SpoVD as a putative target for StoA. We then demonstrate that SpoVD is a membrane-bound protein with two exposed redox-active cysteine residues. Structural modelling of SpoVD, based on the well characterized orthologue PBP2x of Streptococcus pneumoniae, confirmed that a disulfide bond can form close to the active site of the penicillin-binding domain restricting access of enzyme substrate or functional association with other cortex biogenic proteins. Finally, by exploiting combinations of mutations in the spoVD, stoA and ccdA genes in B. subtilis cells, we present strong in vivo evidence that supports the conclusion that StoA functions to specifically break the disulfide bond in the SpoVD protein in the forespore envelope. The findings contribute to our understanding of endospore biogenesis and open a new angle to regulation of cell wall synthesis and penicillin-binding protein activity.
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| 10. |
- Simon, Jörg, et al.
(författare)
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Composition and function of cytochrome c biogenesis System II.
- 2011
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Ingår i: The FEBS Journal. - : Wiley. - 1742-464X. ; 278:22, s. 4179-4188
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Tidskriftsartikel (refereegranskat)abstract
- Organisms employ one of several different enzyme systems to mature cytochromes c. The biosynthetic process involves the periplasmic reduction of cysteine residues in the heme c attachment motif of the apocytochrome, transmembrane transport of heme b and stereospecific covalent heme attachment via thioether bonds. The biogenesis System II (or Ccs system) is employed by β-, δ- and ε-proteobacteria, Gram-positive bacteria, Aquificales and cyanobacteria, as well as by algal and plant chloroplasts. System II comprises four (sometimes only three) membrane-bound proteins: CcsA (or ResC) and CcsB (ResB) are the components of the cytochrome c synthase, whereas CcdA and CcsX (ResA) function in the generation of a reduced heme c attachment motif. Some ε-proteobacteria contain CcsBA fusion proteins constituting single polypeptide cytochrome c synthases especially amenable for functional studies. This minireview highlights the recent findings on the structure, function and specificity of individual System II components and outlines the future challenges that remain to our understanding of the fascinating post-translational protein maturation process in more detail.
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