| 1. |
- Ahuja, Umesh, et al.
(författare)
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Haem-delivery proteins in cytochrome c maturation System II
- 2009
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Ingår i: Molecular Microbiology. - : Wiley. - 1365-2958 .- 0950-382X. ; 73:6, s. 1058-1071
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Tidskriftsartikel (refereegranskat)abstract
- P>Cytochromes of the c-type function on the outer side of the cytoplasmic membrane in bacteria where they also are assembled from apo-cytochrome polypeptide and haem. Two distinctly different systems for cytochrome c maturation are found in bacteria. System I present in Escherichia coli has eight to nine different Ccm proteins. System II is found in Bacillus subtilis and comprises four proteins: CcdA, ResA, ResB and ResC. ResB and ResC are poorly understood polytopic membrane proteins required for cytochrome c synthesis. We have analysed these two B. subtilis proteins produced in E. coli and in the native organism. ResB is shown to bind protohaem IX and haem is found covalently bound to residue Cys-138. Results in B. subtilis suggest that also ResC can bind haem. Our results complement recent findings made with Helicobacter CcsBA supporting the hypothesis that ResBC as a complex translocates haem by attaching it to ResB on the cytoplasmic side of the membrane and then transferring it to an extra-cytoplasmic location in ResC, from where it is made available to the apo-cytochromes.
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| 2. |
- Bendz, Maria, et al.
(författare)
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Quantification of Membrane Proteins Using Nonspecific Protease Digestions
- 2009
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Ingår i: Journal of Proteome Research. - : American Chemical Society (ACS). - 1535-3893 .- 1535-3907. ; 8:12, s. 5666-5673
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Tidskriftsartikel (refereegranskat)abstract
- We present a mass spectrometry-based method for the identification and quantification of membrane proteins using the low-specificity protease Proteinase K, at very high pH, to digest proteins isolated by a modified SDS-PAGE protocol. The resulting peptides are modified with a fragmentation-directing isotope labeled tag. We apply the method to quantify differences in membrane protein expression of Bacillus subtilis grown in the presence or absence of glucose.
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| 3. |
- Carlsson Möller, Mirja, et al.
(författare)
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Extracytoplasmatic processes impaired by inactivation of the trxA (thioredoxin gene) in Bacillus subtilis
- 2008
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Ingår i: Journal of Bacteriology. - 0021-9193. ; 190:13, s. 4660-4665
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Tidskriftsartikel (refereegranskat)abstract
- The trxA gene is regarded as essential in Bacillus subtilis, but the roles of the TrxA protein in this gram-positive bacterium are largely unknown. Inactivation of trxA results in deoxyribonucleoside and cysteine or methionine auxotrophy. This phenotype is expected if the TrxA protein is important for the activity of the class Ib ribonucleotide reductase and adenosine-5'-phosphosulfate/3'-phosphoadenosine-5'-phosphosulfate reductase. We demonstrate here that a TrxA deficiency in addition causes defects in endospore and cytochrome c synthesis. These effects were suppressed by BdbD deficiency, indicating that TrxA in the cytoplasm is the primary electron donor to several different thiol-disulfide oxidoreductases active on the outer side of the B. subtilis cytoplasmic membrane.
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| 4. |
- Carlsson Möller, Mirja, et al.
(författare)
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Role of membrane-bound thiol-disulfide oxidoreductases in endospore-forming bacteria
- 2006
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Ingår i: Antioxidants & Redox Signaling. - : Mary Ann Liebert Inc. - 1557-7716 .- 1523-0864. ; 8:5-6, s. 823-833
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Forskningsöversikt (refereegranskat)abstract
- Thiol-disulfide oxidoreductases catalyze formation, disruption, or isomerization of disulfide bonds between cysteine residues in proteins. Much is known about the functional roles and properties of this class of redox enzymes in vegetative bacterial cells but their involvement in sporulation has remained unknown until recently. Two membrane-embedded thiol-disulfide oxidoreductases, CcdA and StoA/SpoIVH, conditionally required for efficient production of Bacillus subtilis heat-resistant endospores, have now been identified. Properties of mutant cells lacking the two enzymes indicate new aspects in the molecular details of endospore envelope development. This mini-review presents an overview of membrane-bound thiol-disulfide oxidoreductases in the Gram-positive bacterium B. subtilis and endospore synthesis. Accumulated experimental findings on CcdA and StoA/SpoIVH are reviewed. A model for the role of these proteins in endospore cortex biogenesis in presented.
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| 5. |
- Crow, Allister, et al.
(författare)
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Crystal structure and biophysical properties of Bacillus subtilis BdbD: An oxidizing thiol:disulfide oxidoreductase containing a novel metal site
- 2009
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Ingår i: Journal of Biological Chemistry. - 1083-351X. ; 284:35, s. 23719-23733
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Tidskriftsartikel (refereegranskat)abstract
- BdbD is a thiol: disulfide oxidoreductase (TDOR) from Bacillus subtilis that functions to introduce disulfide bonds in substrate proteins/peptides on the outside of the cytoplasmic membrane and, as such, plays a key role in disulfide bond management. Here we demonstrate that the protein is membrane-associated in B. subtilis and present the crystal structure of the soluble part of the protein lacking its membrane anchor. This reveals that BdbD is similar in structure to Escherichia coli DsbA, with a thioredoxin-like domain with an inserted helical domain. A major difference, however, is the presence in BdbD of a metal site, fully occupied by Ca2+, at an inter-domain position some 14 angstrom away from the CXXC active site. The midpoint reduction potential of soluble BdbD was determined as -75 mV versus normal hydrogen electrode, and the active site N-terminal cysteine thiol was shown to have a low pK(a), consistent with BdbD being an oxidizing TDOR. Equilibrium unfolding studies revealed that the oxidizing power of the protein is based on the instability introduced by the disulfide bond in the oxidized form. The crystal structure of Ca2+-depleted BdbD showed that the protein remained folded, with only minor conformational changes. However, the reduced form of Ca2+-depleted BdbD was significantly less stable than reduced Ca2+-containing protein, and the midpoint reduction potential was shifted by approximately -20 mV, suggesting that Ca2+ functions to boost the oxidizing power of the protein. Finally, we demonstrate that electron exchange does not occur between BdbD and B. subtilis ResA, a low potential extra-cytoplasmic TDOR.
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| 6. |
- Crow, Allister, et al.
(författare)
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Structure and Functional Properties of Bacillus subtilis Endospore Biogenesis Factor StoA
- 2009
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Ingår i: Journal of Biological Chemistry. - 1083-351X. ; 284:15, s. 10056-10066
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Tidskriftsartikel (refereegranskat)abstract
- Bacillus subtilis StoA is an extracytoplasmic thiol-disulfide oxidoreductase (TDOR) important for the synthesis of the endospore peptidoglycan cortex protective layer. Here we demonstrate that StoA is membrane-associated in B. subtilis and report the crystal structure of the soluble protein lacking its membrane anchor. This showed that StoA adopts a thioredoxin-like fold with N-terminal and internal additions that are characteristic of extracytoplasmic TDORs. The CXXC active site of the crystallized protein was found to be in a mixture of oxidized and reduced states, illustrating that there is little conformational variation between redox states. The midpoint reduction potential was determined as -248 mV versus normal hydrogen electrode at pH 7 consistent with StoA fulfilling a reductive role in endospore biogenesis. pKa values of the active site cysteines, Cys-65 and Cys-68, were determined to be 5.5 and 7.8. Although Cys-68 is buried within the structure, both cysteines were found to be accessible to cysteine-specific alkylating reagents. In vivo studies of site-directed variants of StoA revealed that the active site cysteines are functionally important, as is Glu-71, which lies close to the active site and is conserved in many reducing extracytoplasmic TDORs. The structure and biophysical properties of StoA are very similar to those of ResA, a B. subtilis extracytoplasmic TDOR involved in cytochrome c maturation, raising important general questions about how these similar but non-redundant proteins achieve specificity. A detailed comparison of the two proteins demonstrates that relatively subtle differences, largely located around the active sites of the proteins, are sufficient to confer specificity.
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| 7. |
- Geisler, Daniela, et al.
(författare)
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Ca2+-binding and Ca2+-independent respiratory NADH and NADPH dehydrogenases of Arabidopsis thaliana.
- 2007
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Ingår i: Journal of Biological Chemistry. - 1083-351X. ; 282:39, s. 28455-28464
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Tidskriftsartikel (refereegranskat)abstract
- Type II NAD(P)H:quinone oxidoreductases are single polypeptide proteins widespread in the living world. They bypass the first site of respiratory energy conservation, constituted by the type I NADH dehydrogenases. To investigate substrate specificities and Ca2+ binding properties of seven predicted type II NAD(P)H dehydrogenases of Arabidopsis thaliana we have produced them as T7-tagged fusion proteins in Escherichia coli. The NDB1 and NDB2 enzymes were found to bind Ca2+, and a single amino acid substitution in the EF hand motif of NDB1 abolished the Ca2+ binding. NDB2 and NDB4 functionally complemented an E. coli mutant deficient in endogenous type I and type II NADH dehydrogenases. This demonstrates that these two plant enzymes can substitute for the NADH dehydrogenases in the bacterial respiratory chain. Three NDB-type enzymes displayed distinct catalytic profiles with substrate specificities and Ca2+ stimulation being considerably affected by changes in pH and substrate concentrations. Under physiologically relevant conditions, the NDB1 fusion protein acted as a Ca2+-dependent NADPH dehydrogenase. NDB2 and NDB4 fusion proteins were NADH-specific, and NDB2 was stimulated by Ca2+. The observed activity profiles of the NDB-type enzymes provide a fundament for understanding the mitochondrial system for direct oxidation of cytosolic NAD(P)H in plants. Our findings also suggest different modes of regulation and metabolic roles for the analyzed A. thaliana enzymes.
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| 8. |
- Hederstedt, Lars, et al.
(författare)
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Heme A synthase enzyme functions dissected by mutagenesis of Bacillus subtilis CtaA
- 2005
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Ingår i: Journal of Bacteriology. - 0021-9193. ; 187:24, s. 8361-8369
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Tidskriftsartikel (refereegranskat)abstract
- Heme A, as a prosthetic group, is found exclusively in respiratory oxidases of mitochondria and aerobic bacteria. Bacillus subtilis CtaA and other heme A synthases catalyze the conversion of a methyl side group on heme 0 into a formyl group. The catalytic mechanism of heme A synthase is not understood, and little is known about the composition and structure of the enzyme. In this work, we have: (i) constructed a ctaA deletion mutant and a system for overproduction of mutant variants of the CtaA protein in B. subtilis, (ii) developed an affinity purification procedure for isolation of preparative amounts of CtaA, and (iii) investigated the functional roles of four invariant histidine residues in heme A synthase by in vivo and in vitro analyses of the properties of mutant variants of CtaA. Our results show an important function of three histidine residues for heme A synthase activity. Several of the purified mutant enzyme proteins contained tightly bound heme O. One variant also contained trapped hydroxylated heme 0, which is a postulated enzyme reaction intermediate. The findings indicate functional roles for the invariant histidine residues and provide strong evidence that the heme A synthase enzyme reaction includes two consecutive monooxygenations.
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| 9. |
- Hodson, Christopher, et al.
(författare)
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The active-site cysteinyls and hydrophobic cavity residues of resA are important for cytochrome c maturation in Bacillus subtilis
- 2008
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Ingår i: Journal of Bacteriology. - 0021-9193. ; 190:13, s. 4697-4705
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Tidskriftsartikel (refereegranskat)abstract
- ResA is an extracytoplasmic membrane-bound thiol-disulfide oxidoreductase required for cytochrome c maturation in Bacillus subtilis. Previous biochemical and structural studies have revealed that the active-site cysteinyls cycle between oxidized and reduced states with a low reduction potential and that, upon reduction, a hydrophobic cavity forms close to the active site. Here we report in vivo studies of ResA-deficient B. subtilis complemented with a series of ResA variants. Using a range of methods to analyze the cellular cytochrome c content, we demonstrated (i) that the N-terminal transmembrane segment of ResA serves principally to anchor the protein to the cytoplasmic membrane but also plays a role in mediating the activity of the protein; (ii) that the active-site cysteines are important for cytochrome c maturation activity; (iii) that Pro141, which forms part of the hydrophobic cavity and which adopts a cis conformation, plays an important role in protein stability; (iv) that Glu80, which lies at the base of the hydrophobic cavity, is important for cytochrome c maturation activity; and, finally, (v) that Pro141 and Glu80 ResA mutant variants promote selective maturation of low levels of one c-type cytochrome, subunit II of the cytochrome c oxidase caa(3), indicating that this apocytochrome is distinct from the other three endogenous c-type cytochromes of B. subtilis.
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| 10. |
- Lewin, Anna, et al.
(författare)
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Compact archaeal variant of heme A synthase
- 2006
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Ingår i: FEBS Letters. - : Wiley. - 1873-3468 .- 0014-5793. ; 580:22, s. 5351-5356
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Tidskriftsartikel (refereegranskat)abstract
- The N- and C-terminal halves of the heme A synthase polypeptide of Bacillus subtilis, and many other organisms, are homologous. This indicates that these enzyme proteins originate from a tandem duplication and fusion event of a gene encoding a protein half as large. The ape1694 gene of the hyperthermophilic archaeon Aeropyrum pernix encodes a protein that is similar to the hypothetical small primordial protein. We demonstrate that this A. pernix protein is a heat-stable membrane bound heme A synthase designated cCtaA. The case of cCtaA is unusual in evolution in that the primordial-like protein has not become extinct and apparently carries out the same function as the twice as large more diversified heme A synthase protein variant found in most cytochrome a-containing organisms.
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| 11. |
- Lewin, Allison, et al.
(författare)
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Effects of substitutions in the CXXC active-site motif of the extracytoplasmic thioredoxin ResA
- 2008
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Ingår i: Biochemical Journal. - 0264-6021. ; 414, s. 81-91
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Tidskriftsartikel (refereegranskat)abstract
- The thiol-disulfide oxidoreductase ResA from Bacillus subtilis fulfils a reductive role in cytochrome c maturation. The pK(a) values for the CEPC (one-letter code) active-site cysteine residues of Ill are unusual for thioredoxin-like proteins ill that they are both high (> 8) and within 0.5 unit of each other. To determine the contribution of the inter-cysteine dipeptide of ResA to its redox and acid-base properties, three variants (CPPC, CEHC and CPHC) were generated representing a stepwise conversion into the active-site sequence of the high-potential DsbA protein from Escherichia coli. The substitutions resulted in large decreases in the pK(a) values of both the active-site cysteine residues: in CPHC (DsbA-type) ResA, Delta pK(a) values of -2.5 were measured for both cysteine residues. Increases in midpoint reduction potentials were also observed, although these were comparatively small: CPHC (DsbA-type) ResA exhibited all increase of +40mV compared with the wild-type protein. Unfolding studies revealed that, despite the observed differences in the properties of the reduced proteins, changes in stability were largely confined to file oxidized state. High-resolution structures of two of the variants (CEHC and CPHC ResA) in their reduced states were determined and are discussed in terms of the observed changes ill properties. Finally, the in vivo functional properties of CEHC RcsA are shown to be significantly affected compared with those of the wild-type protein.
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| 12. |
- Lewin, Anna, et al.
(författare)
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Positively Regulated Glycerol/G3P-Dependent Bacillus subtilis Gene Expression System Based on Anti-Termination.
- 2009
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Ingår i: Journal of Molecular Microbiology and Biotechnology. - : S. Karger AG. - 1464-1801. ; 17, s. 61-70
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Tidskriftsartikel (refereegranskat)abstract
- Plasmid pLALA was constructed for glycerol or glycerol-3-phosphate inducible plasmid-borne gene expression in Bacillus subtilis and closely related Gram-positive bacteria. Gene expression using pLALA is based on anti-termination of transcription and involves the B. subtilis GlpP protein that in the presence of glycerol-3-phosphate acts as an anti-terminator protein by binding to the 5'-untranslated region of glpD mRNA. Properties and the usefulness of the system, denoted LALA, were validated by inducible production in B. subtilis strainsof two water-soluble proteins (beta-galactosidase and a protein phospho-tyrosine phosphatase), and one integral membrane protein (heme A synthase). Advantages with LALA is that it is based on positive control, does not involve a DNA-binding protein, and that glycerol, a cheap and stable compound, can be used as inducer of gene expression.
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| 13. |
- Lewin, Anna, et al.
(författare)
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Promoted evolution of a shortened variant of heme A synthase in the membrane of Bacillus subtilis.
- 2008
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Ingår i: FEBS Letters. - : Wiley. - 1873-3468 .- 0014-5793. ; 582, s. 1330-1334
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Tidskriftsartikel (refereegranskat)abstract
- Bacillus subtilis heme A synthase is a membrane protein with 8 transmembrane segments. By using a two-step mutagenesis approach we have generated and selected a fully functional enzyme protein variant with a seven residue internal deletion. The biochemical properties of the shortened variant are similar to those of the normal enzyme. This could indicate that residue H209 in the mutant protein substitutes for the missing H216 as an axial ligand to the heme iron. Our results provide insight in routes of membrane protein evolution and the structure of heme A synthases.
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| 14. |
- Liu, Cong, et al.
(författare)
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Preparation, crystallization and preliminary X-ray analysis of protein YtlP from Bacillus subtilis
- 2006
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Ingår i: Acta Crystallographica. Section F: Structural Biology and Crystallization Communications. - 2053-230X. ; 62:10, s. 967-969
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Tidskriftsartikel (refereegranskat)abstract
- Bacillus subtilis YtlP is a protein that is predicted to belong to the bacterial and archael 2'-5' RNA-ligase family. It contains 183 residues and two copies of the HXTX sequence motif conserved among proteins belonging to this family. In order to determine the structure of YtlP and to compare it with the paralogue YjcG and identified 2'-5' RNA ligases, the gene ytlP was amplified from B. subtilis genomic DNA and cloned into expression vector pET-21a. The soluble protein was produced in Escherichia coli, purified to homogeneity and crystals suitable for X-ray analysis were obtained. The crystal diffracted to 2.0 angstrom and belonged to space group P2(1)2(1)2(1), with unit-cell parameters a = 34.16, b = 48.54, c = 105.75 angstrom.
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| 15. |
- Persson Sunde, Erik, et al.
(författare)
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The physical state of water in bacterial spores.
- 2009
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Ingår i: Proceedings of the National Academy of Sciences. - : Proceedings of the National Academy of Sciences. - 1091-6490 .- 0027-8424. ; 106:46, s. 19334-19339
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Tidskriftsartikel (refereegranskat)abstract
- The bacterial spore, the hardiest known life form, can survive in a metabolically dormant state for many years and can withstand high temperatures, radiation, and toxic chemicals. The molecular basis of spore dormancy and resistance is not understood, but the physical state of water in the different spore compartments is thought to play a key role. To characterize this water in situ, we recorded the water 2H and 17O spin relaxation rates in D2O-exchanged Bacillus subtilis spores over a wide frequency range. The data indicate high water mobility throughout the spore, comparable with binary protein–water systems at similar hydration levels. Even in the dense core, the average water rotational correlation time is only 50 ps. Spore dormancy therefore cannot be explained by glass-like quenching of molecular diffusion but may be linked to dehydration-induced conformational changes in key enzymes. The data demonstrate that most spore proteins are rotationally immobilized, which may contribute to heat resistance by preventing heat-denatured proteins from aggregating irreversibly. We also find that the water permeability of the inner membrane is at least 2 orders of magnitude lower than for model membranes, consistent with the reported high degree of lipid immobilization in this membrane and with its proposed role in spore resistance to chemicals that damage DNA. The quantitative results reported here on water mobility and transport provide important clues about the mechanism of spore dormancy and resistance, with relevance to food preservation, disease prevention, and astrobiology.
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| 16. |
- Zoppellaro, Giorgio, et al.
(författare)
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Studies of Ferric Heme Proteins with Highly Anisotropic/Highly Axial Low Spin (S=1/2) Electron Paramagnetic Resonance Signals with bis-Histidine and Histidine-Methionine Axial Iron Coordination
- 2009
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Ingår i: Biopolymers. - : Wiley. - 0006-3525 .- 1097-0282. ; 91:12, s. 1064-1082
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Forskningsöversikt (refereegranskat)abstract
- Six-coordinated heme groups are involved in a large variety of electron transfer reactions because of their ability to exist in both the ferrous (Fe2+) andferric (Fe3+) state without any large differences in structure. Our studies on hemes coordinated by two histidines (bis-His) and hemes coordinated by histidine and methionine (His-Met) will be reviewed. In both of these coordination environments, the heme core can exhibit ferric low spin (electron paramagnetic resonance EPR) signals with large g(max) values (also called Type I, highly anisotropic low spin, or highly axial low spin, HALS species) as Well as rhombic EPR (Type II) signals. In bis-His coordinated hemes rhombic and HALS envelopes are related to the orientation of the His groups with respect to each other such that (i) parallel His planes results in a rhombic signal and (ii) perpendicular His planes results in a HALS signal. Correlation between the structure of the heme and its ligands for heme with His-Met axial ligation and ligand-field parameters, as derived from a large series of cytochrome c variants, show, however, that for such a combination of axial ligands there is no clear-cut difference between the large g(max) and the "small ganisotropy" cases as a result of the relative Met-His arrangements. Nonetheless, a new linear correlation links the average shift of the heme methyl groups with the g(max) values. (c) 2009 Wiley Periodicals, Inc. Biopolymers 91: 1064-1082, 2009.
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