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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 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
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
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
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
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
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
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
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
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
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 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
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
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
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
The citric acid cycle (CAC) has several functions in aerobic bacteria. Together with the pyruvate dehydrogenase multienzyme complex (PDHC), it completely oxidizes pyruvate and provides membrane-bound respiratory systems with reducing equivalents. An overview of the biochemistry and genetics of CAC enzymes in B. subtilis is presented in this chapter. B. subtilis, being a strict aerobe, runs a compl
Cytochrome c-550 of the Gram-positive bacterium, Bacillus subtilis, is a membrane-bound 13-kDa protein encoded by the cccA gene. The cytochrome has been proposed to be comprised of an N-terminal membrane anchor domain (about 30 residues) which spans the cytoplasmic membrane in an alpha-helical conformation and a C-terminal heme domain (about 70 residues) which is located on the outside of the cyto
Bacillus subtilis cells must have cytochromes for growth and can synthesize cytochromes of a-, b-, c-, d-, and o-types. After a long lag, our knowledge of the structure, genetics and specific role for these cytochromes is now growing exponentially as the result of recent research. This progress is reviewed here and includes, for example, the discovery of two different cytochrome a systems and gene
Solution-processed organometal halide perovskites are hybrid crystalline semiconductors highly interesting for low-cost and efficient optoelectronics. Their properties are dependent on the crystal structure. Literature shows a variety of crystal phase transition temperatures and often a spread of the transition over tens of degrees Kelvin. We explain this inconsistency by demonstrating that the te
Succinate:menaquinone-7 oxidoreductase (complex II) of the Gram-positive bacterium B subtilis consists of equimolar amounts of three polypeptides; a 65-kDa FAD-containing polypeptide, a 28-kDa iron-sulfur cluster containing polypeptide, and a 23-kDa membrane-spanning cytochrome b558 polypeptide, The enzyme complex was overproduced 2-3-fold in membranes of B. subtilis cells containing the sdhCAB op
