The succinate:menaquinone reductase of Bacillus cereus — characterization of the membrane-bound and purified enzyme

2008 ◽  
Vol 54 (6) ◽  
pp. 456-466 ◽  
Author(s):  
L.M. García ◽  
M.L. Contreras-Zentella ◽  
R. Jaramillo ◽  
M.C. Benito-Mercadé ◽  
G. Mendoza-Hernández ◽  
...  
Keyword(s):  
Bacillus Cereus ◽  
Cytochrome B ◽  
Kinetic Studies ◽  
Opportunistic Pathogen ◽  
Molecular Characteristics ◽  
Uptake System ◽  
Absorption Bands ◽  
Genome Database ◽  
Midpoint Potential ◽  
Maximal Absorption

Utilization of external succinate by Bacillus cereus and the properties of the purified succinate:menaquinone-7 reductase (SQR) were studied. Bacillus cereus cells showed a poor ability for the uptake of and respiratory utilization of exogenous succinate, thus suggesting that B. cereus lacks a specific succinate uptake system. Indeed, the genes coding for a succinate–fumarate transport system were missing from the genome database of B. cereus. Kinetic studies of membranes indicated that the reduction of menaquinone-7 is the rate-limiting step in succinate respiration. In accordance with its molecular characteristics, the purified SQR of B. cereus belongs to the type-B group of SQR enzymes, consisting of a 65-kDa flavoprotein (SdhA), a 29-kDa iron–sulphur protein (SdhB), and a 19-kDa subunit containing 2 b-type cytochromes (SdhC). In agreement with this, we could identify the 4 conserved histidines in the SdhC subunit predicted by the B. cereus genome database. Succinate reduced half of the cytochrome b content. Redox titrations of SQR-cytochrome b-557 detected 2 components with apparent midpoint potential values at pH 7.6 of 79 and –68 mV, respectively; the components were not spectrally distinguishable by their maximal absorption bands as those of Bacillus subtilis . The physiological properties and genome database analyses of B. cereus are consistent with the cereus group ancestor being an opportunistic pathogen.

scholarly journals Cytochrome b-562 from Acinetobacter calcoaceticus L.M.D. 79.41. Its characteristics and role as electron acceptor for quinoprotein glucose dehydrogenase

1988 ◽  
Vol 254 (1) ◽  
pp. 131-138 ◽  
Author(s):  
P Dokter ◽  
J E van Wielink ◽  
M A G van Kleef ◽  
J A Duine
Keyword(s):  
Cytochrome B ◽  
Electron Acceptor ◽  
Glucose Dehydrogenase ◽  
Acinetobacter Calcoaceticus ◽  
Primary Electron ◽  
Reduced Form ◽  
Alpha Band ◽  
Absorption Bands ◽  
Midpoint Potential ◽  
Triton X

A soluble cytochrome b was purified from Acinetobacter calcoaceticus L.M.D. 79.41. On the basis of the alpha-band maximum of a reduced preparation, measured at 25 degrees C, it is designated as cytochrome b-562. This cytochrome is a basic monomeric protein (pI 10.2; Mr 18,000), containing one protohaem group per molecule. The reduced form, at 25 degrees C, showed absorption bands at 428, 532 and 562 nm. At 77 K the alpha-band shifted to 560 nm (with a shoulder at 558 nm). The reduced cytochrome did not react with CO. Cytochrome b-562 is most probably (loosely) attached to the outside of the cytoplasmic membrane, since substantial amounts of it, equimolar to quinoprotein glucose dehydrogenase (GDH), were present in the culture medium when cells were grown in the presence of low concentrations of Triton X-100. The midpoint potential at pH 7.0 was found to be +170 mV, a value that was lowered to +145 mV by the presence of GDH. Since the GDH was shown to have a midpoint potential of +50 mV, cytochrome b-562 could function as the natural primary electron acceptor. Arguments to substantiate this view and to propose a role of ubiquinone-9 as electron acceptor for cytochrome b-562 are presented.

Oxidation–reduction titration of cytochrome components in the electron transport chain of Azotobacter vinelandii

1981 ◽  
Vol 59 (2) ◽  
pp. 137-144 ◽  
Author(s):  
Tsanyen Yang
Keyword(s):  
Electron Transport ◽  
Cytochrome B ◽  
Absorption Maximum ◽  
Azotobacter Vinelandii ◽  
Reactive Component ◽  
Midpoint Potential ◽  
Oxidation Reduction ◽  
Membrane Bound ◽  
The Individual ◽  
Cytochrome D

The multiple cytochrome components in the electron transport particle of Azotobacter vinelandii were resolved and their oxidation–reduction midpoint potentials were determined by a simultaneous potentiometric and absorption measurements under anaerobic condition with or without CO. The midpoints of the individual cytochrome component corresponding to the membrane-bound types were also determined in the solubilized fractions prepared by a differential detergent solubilization of the membrane particles of A. vinelandii. Two cytochromes of b type, one with an absorption maximum measured at 559 nm and another at 561 nm in the membrane particle, were resolved and their Em, 7.4 values determined to be −30 mV and +122 mV, respectively. Cytochrome b559 reacted with CO readily in both membrane-bound and solubilized forms, however, cytochrome b561 was inert to CO treatment. Only one cytochrome of c type (c4) measured at 575–551 nm was resolved, its midpoint potential at pH 7.4 was +322 mV in the membrane-bound form and +278 mV in the solubilized form. This c-type cytochrome had no CO reactivity. Cytochrome d, a CO-reactive component, had a midpoint of +270 mV in the membrane fraction. The midpoint of cytochrome a1 in its membrane-bound form could not be measured accurately because of its low concentration. However, in the solubilized preparations, cytochrome a1 apparently had a red shift with an absorption maximum at 613 nm, with an estimated Em, 7.4 of −45 mV, while cytochrome d was no longer detected, possibly because of denaturation.

scholarly journals Quinolone Antibacterials: Commentary and Considerations Regarding UV Spectra and Chemical Structure

2015 ◽  
Vol 61 (4) ◽  
pp. 328-336 ◽  
Author(s):  
Rusu Aura ◽  
Imre Silvia ◽  
Mircia Eleonora ◽  
Hancu Gabriel
Keyword(s):  
Analytical Methods ◽  
Chemical Structure ◽  
Kinetic Studies ◽  
General Characteristic ◽  
Protonated Form ◽  
Uv Spectra ◽  
Spectrophotometric Analysis ◽  
Model Compounds ◽  
Absorption Bands ◽  
Quinolone Derivatives

AbstractObjective: Antibacterial quinolones represent an important class of pharmaceutical compounds that are widely used in therapy. Analytical methods that rely on their property to absorb light in the UV range are commonly used for their analysis. In the current study we present an interpretation of the relationship between chemical structure – UV spectra based on the comparative examination of UV spectral behavior of the eighteen quinolone derivatives and four model compounds.Methods: Eighteen quinolone derivatives and four model compounds were selected and their UV spectra were recorded in different solvents (methanol, 0.1M HCl, 0.1M NaOH).Results: The studied compounds show three absorption maximum values located around 210-230 nm, 270-300 nm and 315-330 nm values. A general characteristic was observed as the absorption bands exhibited both hypsochrome and bathochrome shifts, by comparison in different solvents. Most commonly we observed a slight hypsochrome shift at acidic pH (protonated form prevails) and basic pH (anionic form prevails). The structural differences are reflected in changes of UV spectra only when there are auxochrom substituents or different basic substituents are present in the quinolones structure.Conclusions: The correlations between the chemical structure of quinolone derivatives and their UV spectra using model compounds were established. This study provides useful information that can be used successfully in various UV spectrophotometric analysis methods or in more complex analytical methods using UV detection, and also in pharmacodynamic and kinetic studies.

Kinetic studies on the oxidation of cytochrome b 5 Phe35 mutants with cytochrome c, plastocyanin and inorganic complexes

2001 ◽  
Vol 7 (4-5) ◽  
pp. 375-383 ◽  
Author(s):  
Ping Yao ◽  
Yun-Hua Wang ◽  
Bing-Yun Sun ◽  
Yi Xie ◽  
Shun Hirota ◽  
...  
Keyword(s):  
Cytochrome C ◽  
Cytochrome B ◽  
Kinetic Studies ◽  
Inorganic Complexes

scholarly journals Oxidation-reduction properties of the cytochrome b found in the plasma-membrane fraction of human neutrophils. A possible oxidase in the respiratory burst

1981 ◽  
Vol 194 (2) ◽  
pp. 599-606 ◽  
Author(s):  
A R Cross ◽  
O T Jones ◽  
A M Harper ◽  
A W Segal
Keyword(s):  
Plasma Membrane ◽  
Cytochrome B ◽  
Plasma Membranes ◽  
Mixing Time ◽  
Human Neutrophils ◽  
Half Time ◽  
Sulphur Compounds ◽  
Midpoint Potential ◽  
Oxidation Reduction ◽  
Membrane Bound

The oxidation-reduction midpoint potential of the cytochrome b found in the plasma membrane of human neutrophils has been determined at pH 7.0 (Em,7.0) from measurements of absorption spectra at fixed potentials. In both unstimulated and phorbol myristate acetate-stimulated cells Em,7.0 was -245 mV. Changes in pH affected the Em of the cytochrome b, with a slope of approx. 25 mV/pH unit change. The Em,7.0 of the haem group(s) of the membrane-bound myeloperoxidase of human neutrophils was found to be +34 mV. The plasma membranes contained no detectable ubiquinone, and no iron-sulphur compounds were detected by e.p.r. spectroscopy at 5-20 K. No flavins were detected by e.p.r. spectroscopy. The cytochrome b-245 was not reduced by added NADH or NADPH. Dithionite-reduced cytochrome b-245 formed a complex with CO, supplied as a saturated solution, which was dissociated with 26 microseconds illumination from a xenon flash lamp, and the recombination with CO had a half-time of approx. 6 ms. Partly (80%) reduced cytochrome b-245 was oxidized by added air-saturated buffer with a half-time faster than 1 s at 20 degrees C, a resolution limited by mixing time. These results are compatible with cytochrome b-245 acting as an oxidase.

A Ferric Dicitrate Uptake System Is Required for the Full Virulence of Bacillus cereus

2005 ◽  
Vol 50 (5) ◽  
pp. 246-250 ◽  
Author(s):  
Duncan R. Harvie ◽  
David J. Ellar
Keyword(s):  
Bacillus Cereus ◽  
Uptake System

scholarly journals Flexible Cobamide Metabolism in Clostridioides (Clostridium) difficile 630 Δerm

2019 ◽  
Vol 202 (2) ◽  
Author(s):  
Amanda N. Shelton ◽  
Xun Lyu ◽  
Michiko E. Taga
Keyword(s):  
De Novo ◽  
Aminolevulinic Acid ◽  
Genomic Analysis ◽  
Opportunistic Pathogen ◽  
Vitamin B ◽  
Uptake System ◽  
Human Gut ◽  
Content Type ◽  
Clostridioides Difficile

ABSTRACT Clostridioides (Clostridium) difficile is an opportunistic pathogen known for its ability to colonize the human gut under conditions of dysbiosis. Several aspects of its carbon and amino acid metabolism have been investigated, but its cobamide (vitamin B12 and related cofactors) metabolism remains largely unexplored. C. difficile has seven predicted cobamide-dependent pathways encoded in its genome in addition to a nearly complete cobamide biosynthesis pathway and a cobamide uptake system. To address the importance of cobamides to C. difficile, we studied C. difficile 630 Δerm and mutant derivatives under cobamide-dependent conditions in vitro. Our results show that C. difficile can use a surprisingly diverse array of cobamides for methionine and deoxyribonucleotide synthesis and can use alternative metabolites or enzymes, respectively, to bypass these cobamide-dependent processes. C. difficile 630 Δerm produces the cobamide pseudocobalamin when provided the early precursor 5-aminolevulinic acid or the late intermediate cobinamide (Cbi) and produces other cobamides if provided an alternative lower ligand. The ability of C. difficile 630 Δerm to take up cobamides and Cbi at micromolar or lower concentrations requires the transporter BtuFCD. Genomic analysis revealed genetic variations in the btuFCD loci of different C. difficile strains, which may result in differences in the ability to take up cobamides and Cbi. These results together demonstrate that, like other aspects of its physiology, cobamide metabolism in C. difficile is versatile. IMPORTANCE The ability of the opportunistic pathogen Clostridioides difficile to cause disease is closely linked to its propensity to adapt to conditions created by dysbiosis of the human gut microbiota. The cobamide (vitamin B12) metabolism of C. difficile has been underexplored, although it has seven metabolic pathways that are predicted to require cobamide-dependent enzymes. Here, we show that C. difficile cobamide metabolism is versatile, as it can use a surprisingly wide variety of cobamides and has alternative functions that can bypass some of its cobamide requirements. Furthermore, C. difficile does not synthesize cobamides de novo but produces them when given cobamide precursors. A better understanding of C. difficile cobamide metabolism may lead to new strategies to treat and prevent C. difficile-associated disease.

scholarly journals Molecular Characteristics of Cytochrome B for Mackerel Barcoding

2016 ◽  
Vol 19 (1) ◽  
pp. 9 ◽  
Author(s):  
Deden Yusman Maulid ◽  
Mala Nurilmala ◽  
Nurjanah Nurjanah ◽  
Hawis Maddupa
Keyword(s):  
Molecular Weight ◽  
Phylogenetic Analysis ◽  
Mitochondrial Dna ◽  
Cytochrome B ◽  
Pcr Amplification ◽  
3D Modelling ◽  
Molecular Characteristics ◽  
Cyt B ◽  
Scomberomorus Commerson ◽  
King Mackerel

<p>Cytochrome b (cyt b) is one of the genes in mitochondrial DNA that is often used as a molecular<br />marker to identify species through DNA Barcoding. The aim of the present study was to investigate the<br />bioinformatic of cyt b that isolated from mackerel fish. PCR amplification showed the length of DNA cyt<br />b from king mackerel was 803 bp within purine 312 bp and pyrimidine 491 bp while Korean mackerel 791<br />bp within purine 316 bp and pyrimidine 475 bp. Phylogenetic analysis showed all sample join in mackerel<br />groups (Scomberomorus commerson and Scomberomorus koreanus). The Isoelectric point value of cyt b from<br />king mackerel is 6.38 and molecular weight is 29826.23; Korean mackerel are 8.67 and molecular weight is<br />29372.77. Hydrophaty plot showed cyt b of mackerel more hydrophobic. Based on 3D modelling both of<br />them have eight different sections showing by different colors.<br />Keywords: characteristic molecular, cytochrome b, Mackerel<br /><br /></p>

scholarly journals Diverse conjugative elements silence natural transformation inLegionellaspecies

2019 ◽  
Vol 116 (37) ◽  
pp. 18613-18618 ◽  
Author(s):  
Isabelle Durieux ◽  
Christophe Ginevra ◽  
Laetitia Attaiech ◽  
Kévin Picq ◽  
Pierre-Alexandre Juan ◽  
...  
Keyword(s):  
Legionella Pneumophila ◽  
Genome Wide Association Study ◽  
Natural Transformation ◽  
Opportunistic Pathogen ◽  
Conjugative Plasmid ◽  
Uptake System ◽  
Dna Uptake ◽  
Major Mechanism ◽  
A Genome ◽  
Close Relatives

Natural transformation (i.e., the uptake of DNA and its stable integration in the chromosome) is a major mechanism of horizontal gene transfer in bacteria. Although the vast majority of bacterial genomes carry the genes involved in natural transformation, close relatives of naturally transformable species often appear not competent for natural transformation. In addition, unexplained extensive variations in the natural transformation phenotype have been reported in several species. Here, we addressed this phenomenon by conducting a genome-wide association study (GWAS) on a panel of isolates of the opportunistic pathogenLegionella pneumophila. GWAS revealed that the absence of the transformation phenotype is associated with the conjugative plasmid pLPL. The plasmid inhibits transformation by simultaneously silencing the genes required for DNA uptake and recombination. We identified a small RNA (sRNA), RocRp, as the sole plasmid-encoded factor responsible for the silencing of natural transformation. RocRp is homologous to the highly conserved and chromosome-encoded sRNA RocR which controls the transient expression of the DNA uptake system. Assisted by the ProQ/FinO-domain RNA chaperone RocC, RocRp acts as a substitute of RocR, ensuring that the bacterial host of the conjugative plasmid does not become naturally transformable. Distinct homologs of this plasmid-encoded sRNA are found in diverse conjugative elements in otherLegionellaspecies. Their low to high prevalence may result in the lack of transformability of some isolates up to the apparent absence of natural transformation in the species. Generally, our work suggests that conjugative elements obscure the widespread occurrence of natural transformability in bacteria.

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