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Bacillus subtilis contains two small c-type cytochromes with homologous heme-domains but different types of membrane-anchors

We demonstrate that the cccB gene, identified in the Bacillus subtilis genome sequence project, is the structural gene for a 10-kDa membrane-bound cytochrome c551 lipoprotein described for the first time in B. subtilis. Apparently, CccB corresponds to cytochrome c551 of the thermophilic bacterium Bacillus PS3. The heme domain of B. subtilis cytochrome c551 is very similar to that of cytochrome c55

Organisation of genes for tetrapyrrole biosynthesis in Gram-positive bacteria

Clusters of genes encoding enzymes for tetrapyrrole biosynthesis were cloned from Bacillus sphaericus, Bacillus stearothermophilus, Brevibacillus brevis and Paenibacillus macerans. The sequences of all hemX genes found, and of a 6.3 kbp hem gene cluster from P. macerans, were determined. The structure of the hem gene clusters was compared to that of other Gram-positive bacteria. The Bacillus and B

Subunit II of Bacillus subtilis cytochrome c oxidase is a lipoprotein

The sequence of the N-terminal end of the deduced ctaC gene product of Bacillus species has the features of a bacterial lipoprotein. CtaC is the subunit II of cytochrome caa3, which is a cytochrome c oxidase. Using Bacillus subtilis mutants blocked in lipoprotein synthesis, we show that CtaC is a lipoprotein and that synthesis of the membrane-bound protein and covalent binding of heme to the cytoc

The ms2io6A37 modification of tRNA in Salmonella typhimurium regulates growth on citric acid cycle intermediates

The modified nucleoside 2-methylthio-N-6-isopentenyl adenosine (ms(2)i(6)A) is present in position 37 (adjacent to and 3' of the anticodon) of tRNAs that read codons beginning with U except tRNA(I,V)(Ser) in Escherichia coli, In Salmonella typhimurium , 2-methylthio-N-6-(cis-hydroxy)isopentenyl adenosine (ms(2)io(6)A; also referred to as 2-methylthio cis-ribozeatin) is found in tRNA, most likely i

Carboxin resistance in Paracoccus denitrificans conferred by a mutation in the membrane-anchor domain of succinate:quinone oxidoreductase (Complex II)

Succinate:quinone reductase is a membrane-bound enzyme of the citric acid cycle and the respiratory chain. Carboxin is a potent inhibitor of the enzyme of certain organisms. The bacterium Paracoccus denitrificans was found to be sensitive to carboxin in vivo, and mutants that grow in the presence of 3'-methyl carboxin were isolated. Membranes of the mutants showed resistant succinate:quinone reduc

Electron paramagnetic resonance studies of succinate:ubiquinone oxidoreductase from Paracoccus denitrificans : Evidence for a magnetic interaction between the 3Fe-4S cluster and cytochrome b

Electron paramagnetic resonance (EPR) studies of succinate:ubiquinone oxidoreductase (SQR) from Paracoccus denitrificans have been undertaken in the purified and membrane-bound states, Spectroscopic ''signatures'' accounting for the three iron-sulfur clusters (2Fe-2S, 3Fe-4S, and 4Fe-4S), cytochrome b, flavin, and protein-bound ubisemiquinone radicals have been obtained in air-oxidized, succinate-

Escherichia coli ccm in-frame mutants can produce periplasmic cytochrome b but not cytochrome c

Escherichia coli CcmA, CcmB and CcmC polypeptides are required for cytochrome c synthesis and are thought to constitute the subunits of an ABC-type transporter as judged from sequence data, Using a periplasmic reporter system based on Bacillus subtilis cytochrome c-550 and E. coli cytochrome b-562 we show that the synthesis of the b-type cytochrome in the periplasm is normal in E, coli ccmA and cc

Bacillus subtilis CcdA defective mutants are blocked in a late step of cytochrome c biogenesis

Cytochromes of the c type contain covalently bound heme. In bacteria, they are located on the outside of the cytoplasmic membrane. Cytochrome c synthesis involves export of heme and apocytochrome across the cytoplasmic membrane followed by ligation of heme to the polypeptide. Using radioactive protoheme IX produced in Escherichia coli, we show that Bacillus subtilis can use heme from the growth me

Identification and characterization of the ccdA gene, required for cytochrome c synthesis in Bacillus subtilis

The gram-positive, endospore-forming bacterium Bacillus subtilis contains several membrane-bound c-type cytochromes. We have isolated a mutant pleiotropically deficient in cytochromes c. The responsible mutation resides in a gene which we have named ccdA (cytochrome c defective). This gene is located at 173 degrees on the B. subtilis chromosome. The ccdA gene was found to be specifically required

A structural model for the membrane-integral domain of succinate:quinone oxidoreductases

Many succinate:quinone oxidoreductases in bacteria and mitochondria, i.e, succinate:quinone reductases and fumarate reductases, contain in the membrane anchor a cytochrome b whose structure and function is poorly understood, Based on biochemical data and polypeptide sequence information, we show that the anchors in different organisms are related despite an apparent diversity in polypeptide and he

Low spin heme A in the heme A biosynthetic protein CtaA from Bacillus subtilis

Synthesis of heme A from heme B (protoheme IX) most likely occurs in two steps with heme O as an intermediate. Bacillus subtilis CtaB, an integral membrane protein, functions in farnesylation of heme B to form heme O. CtaA, also a membrane protein, is required for heme A synthesis from heme O and appears to be a monooxygenase and/or a dehydrogenase. Wild-type ctaA and ctaB expressed together from

The cytochrome bc complex (menaquinone:cytochrome c reductase) in Bacillus subtilis has a nontraditional subunit organization.

We have identified an operon in Bacillus subtilis, designated qcr, that is thought to encode a quinone: cytochrome c reductase. Northern (RNA blot) analysis suggests a tricistronic operon. The operon is located at about 200 degrees on the B. subtilis map. Disruption of the operon leads to loss of a 22-kDa cytochrome c from membrane preparations. The structure of the putative protein products of th

Transmembrane topology and axial ligands to hemes in the cytochrome b subunit of Bacillus subtilis succinate:menaquinone reductase

The membrane-anchoring subunit of Bacillus subtilis succinate:menaquinone reductase is a protein of 202 residues containing two protoheme IX groups with bis-histidine axial ligation. Residues Kis13, His28, His70, His113, and His155 are the possible heme ligands. The transmembrane topology of this cytochrome was analyzed using fusions to alkaline phosphatase. The results support a proposed model wi

HOQNO interaction with cytochrome b in succinate:menaquinone reductase from Bacillus subtilis

2-n-Heptyl4-hydroxyquinoline-N-oxide (HOQNO) inhibits the succinate:quinone oxidoreductase activity of isolated and membrane-bound succinate:menaquinone oxidoreductase of B. subtilis. The inhibition pattern resembles closely that observed for α-thenoyltrifluoroacetone and carboxins in the mitochondrial succinate:ubiquinone oxidoreductase: ca. 90% of the activity is highly sensitive to HOQNO (K i c

The trinuclear iron-sulfur cluster S-3 in Bacillus subtilis succinate:menaquinone reductase; effects of a mutation in the putative cluster ligation motif on enzyme activity and EPR properties

Succinate:quinone reductases (SQRs) and quinol:fumarate reductases (QFRs) each contain a bi-, a tri- and a tetra-nuclear iron-sulfur cluster. The C-terminal half of the iron-sulfur protein subunit of these enzymes shows two fully conserved motifs of cysteine residues, stereotypical for ligands of [3Fe-4S] and [4Fe-4S] clusters. To analyze the functional role of the trinuclear cluster S3 in Bacillu

Bacillus subtilis CtaA is a heme-containing membrane proteininvolved in heme A biosynthesis

Heme A is a prosthetic group of many respiratory oxidases. It is synthesized from protoheme IX (heme B) seemingly with heme O as a stable intermediate. The Bacillus subtilis ctaA and ctaB genes are required for heme A and heme O synthesis, respectively (B. Svensson, M. Lubben, and L. Hederstedt, Mol. Microbiol. 10:193-201, 1993). Tentatively, CtaA is involved in the monooxygenation and oxidation o

The hemX gene of the Bacillus subtilis hemAXCDBL operon encodes a membrane protein, negatively affecting the steady-state cellular concentration of HemA (glutamyl-tRNA reductase).

The Bacillus subtilis hemAXCDBL operon encodes enzymes for the biosynthesis of uroporphyrinogen III from glutamyl-tRNA. The function of the hemX gene product was studied in this work. The deduced amino acid sequence suggests HemX to be an integral 32 kDa membrane protein. This was confirmed by experiments using Escherichia coli minicells and hemX-phoA gene fusions. Deletion of the hemX gene from t

Enhanced thermal performance of internal Y-shaped bifurcation microchannel heat sinks with metal foams

Internal Y-shaped bifurcation has been proved to be an advantageous way on improvingthermal performance of microchannel heat sinks according to the previous research. Metal foams are known due to their predominate performance such as low-density, largesurface area, and high thermal conductivity. In this paper, different parameters of metalfoams in Y-shaped bifurcation microchannel heat sinks are d

Bacillus subtilis CtaA and CtaB function in haem A biosynthesis

Haem A, a prosthetic group of many respiratory oxidases, is probably synthesized from haem B (protohaem IX) in a pathway in which haem 0 is an intermediate. Possible roles of the Bacillus subtilis ctaA and ctaB gene products in haem 0 and haem A synthesis were studied. Escherichia coli does not contain haem A. The ctaA gene on plasmids in E. coli resulted in haem A accumulation in membranes. The p

Stochastic modelling and optimal spectral estimation of EEG signals

The study of a time-frequency image is often the method of choice to address key issues in cognitive electrophysiology. The quality of the time-frequency representation is crucial for the extraction of robust and relevant features, thus leading to the demand for highly performing spectral estimators. We consider a stochastic model, known as Locally Stationary Processes, based on the modulation in