Search Results - (Author, Cooperation:R. Meganathan)
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1Latest Papers from Table of Contents or Articles in PressM. Vos ; G. Esposito ; J. N. Edirisinghe ; S. Vilain ; D. M. Haddad ; J. R. Slabbaert ; S. Van Meensel ; O. Schaap ; B. De Strooper ; R. Meganathan ; V. A. Morais ; P. Verstreken
American Association for the Advancement of Science (AAAS)
Published 2012Staff ViewPublication Date: 2012-05-15Publisher: American Association for the Advancement of Science (AAAS)Print ISSN: 0036-8075Electronic ISSN: 1095-9203Topics: BiologyChemistry and PharmacologyComputer ScienceMedicineNatural Sciences in GeneralPhysicsKeywords: Adenosine Triphosphate/metabolism ; Animals ; Drosophila/genetics/*metabolism ; Drosophila Proteins/deficiency/*genetics/*metabolism ; *Electron Transport ; Escherichia coli/metabolism ; Flight, Animal ; Genes, Insect ; Membrane Potential, Mitochondrial ; Mitochondria/*metabolism/ultrastructure ; Mitochondria, Muscle/metabolism/ultrastructure ; Mutation ; Oxygen Consumption ; Protein-Serine-Threonine Kinases/deficiency/*genetics/*metabolism ; Ubiquinone/metabolism ; Ubiquitin-Protein Ligases/genetics ; Vitamin K 2/*metabolism/pharmacologyPublished by: -
2Articles: DFG German National LicensesStaff View
ISSN: 0008-6215Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002Topics: Chemistry and PharmacologyType of Medium: Electronic ResourceURL: -
3Articles: DFG German National LicensesStaff View
ISSN: 0014-5793Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002Topics: BiologyChemistry and PharmacologyPhysicsType of Medium: Electronic ResourceURL: -
4Articles: DFG German National LicensesStaff View
ISSN: 0022-5193Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002Topics: BiologyType of Medium: Electronic ResourceURL: -
5Articles: DFG German National LicensesStaff View
ISSN: 1574-6968Source: Blackwell Publishing Journal Backfiles 1879-2005Topics: BiologyNotes: Abstract: Deletion mutants of Escherichia coli lacking dimethyl sulfoxide (DMSO) reductase activity and consequently unable to utilize DMSO as an electron acceptor for anaerobic growth have been isolated. These mutants retained the ability to use trimethylamine N-oxide (TMAO) as an electron acceptor and the TMAO reductase activity was found to be unaltered. Heating the cell-free extract of the wild-type strain at 70°C for 15 min selectively inactivated the DMSO reductase activity while the TMAO reductase activity remained unchanged for at least 1 h.Type of Medium: Electronic ResourceURL: -
6Articles: DFG German National LicensesStaff View
ISSN: 1574-6968Source: Blackwell Publishing Journal Backfiles 1879-2005Topics: BiologyNotes: The quinoid nucleus of the benzoquinone, ubiquinone (coenzyme Q; Q), is derived from the shikimate pathway in bacteria and eukaryotic microorganisms. Ubiquinone is not considered a vitamin since mammals synthesize it from the essential amino acid tyrosine. Escherichia coli and other Gram-negative bacteria derive the 4-hydroxybenzoate required for the biosynthesis of Q directly from chorismate. The yeast, Saccharomyces cerevisiae, can either form 4-hydroxybenzoate from chorismate or tyrosine. However, unlike mammals, S. cerevisiae synthesizes tyrosine in vivo by the shikimate pathway. While the reactions of the pathway leading from 4-hydroxybenzoate to Q are the same in both organisms the order in which they occur differs. The 4-hydroxybenzoate undergoes a prenylation, a decarboxylation and three hydroxylations alternating with three methylation reactions, resulting in the formation of Q. The methyl groups for the methylation reactions are derived from S-adenosylmethionine. While the prenyl side chain is formed by the 2-C-methyl-d-erythritol 4-phosphate (non-mevalonate) pathway in E. coli, it is formed by the mevalonate pathway in the yeast.Type of Medium: Electronic ResourceURL: -
7Articles: DFG German National LicensesStaff View
ISSN: 1574-6968Source: Blackwell Publishing Journal Backfiles 1879-2005Topics: BiologyNotes: Ubiquinone (coenzyme Q; abbreviation, Q) plays an essential role in electron transport in Escherichia coli when oxygen or nitrate is the electron acceptor. The biosynthesis of Q involves at least nine reactions. Three of these reactions involve hydroxylations resulting in the introduction of hydroxyl groups at positions C-6, C-4, and C-5 of the benzene nucleus of Q. The genes encoding the enzymes responsible for these hydroxylations, ubiB, ubiH, and ubiF are located at 87, 66, and 15 min of the E. coli linkage map. The ubiF encoded oxygenase introduces the hydroxyl group at carbon five of 2-octaprenyl-3-methyl-6-methoxy-1,4-benzoquinol resulting in the formation of 2-octaprenyl-3-methyl-5-hydroxy-6-methoxy-1,4-benzoquinol. An ubiF mutant failed to carry out this conversion. Based on the homology to UbiH, an open reading frame (orf391) was identified at the 15 min region of the chromosome, amplified using PCR, and cloned into pUC18 plasmid. The ubiF mutants, when complemented with this plasmid, regained the ability to grow on succinate and synthesize Q.Type of Medium: Electronic ResourceURL: -
8Articles: DFG German National LicensesDaruwala, R. ; Kwon, O. ; Meganathan, R. ; Hudspeth, M.E.S.
Oxford, UK : Blackwell Publishing Ltd
Published 1996Staff ViewISSN: 1574-6968Source: Blackwell Publishing Journal Backfiles 1879-2005Topics: BiologyNotes: Abstract A new gene (menF) encoding an isochorismate synthase specifically involved in menaquinone (vitamin K2) biosynthesis has been cloned and sequenced. Overexpression of the encoded polypeptide under the influence of a T7 promoter showed an increase in specific activity of 2200-fold. Treatment with protamine sulfate resulted in another 3.5-fold increase in specific activity (7700-fold compared to the parent strain). The relative molecular mass of the overexpressed protein was Mr 49 000, which is in full agreement with the DNA sequence predicted molecular mass of 48777 Da. Purified enzyme converted chorismate to isochorismate with the product of the reaction shown to be isochorismate by its thermal conversion to salicylic acid. The fluorescence spectrum generated by the formed salicylic acid was identical to that of authentic salicylic acid. The 5' end of the flanking menD gene has also been redefined.Type of Medium: Electronic ResourceURL: -
9Articles: DFG German National LicensesStaff View
ISSN: 1574-6968Source: Blackwell Publishing Journal Backfiles 1879-2005Topics: BiologyNotes: Abstract Mutants of Escherichia coli blocked in the biosynthesis of menaquinone were unable to use trimethylamine-N-oxide as an electron acceptor in complex medium containing glucose. Trimethylamine-N-oxide reduction and the consequent in-crease in growth could be restored in a menC mutant by either o-succinylbenzoic acid (OSB) or 1,4-dihydroxy-2-naphthoic acid (DHNA). In the case of a menB mutant, growth could not be restored by OSB; but addition of DHNA resulted in the restoration of growth to the full extent. These results are consistent with the metabolic blocks in the respective men mutants.Type of Medium: Electronic ResourceURL: -
10Articles: DFG German National LicensesShaw, Duncan J. ; Robinson, E.Clare ; Meganathan, R. ; Bentley, Ronald ; Guest, John R.
Oxford, UK : Blackwell Publishing Ltd
Published 1983Staff ViewISSN: 1574-6968Source: Blackwell Publishing Journal Backfiles 1879-2005Topics: BiologyType of Medium: Electronic ResourceURL: -
11Articles: DFG German National LicensesStaff View
ISSN: 1476-4687Source: Nature Archives 1869 - 2009Topics: BiologyChemistry and PharmacologyMedicineNatural Sciences in GeneralPhysicsNotes: [Auszug] Microorganisms in the ocean or other bodies of water may be affected significantly by hydrostatic pressure, which increases by about one atmosphere (atm) for every 10 m depth. As early as 1891, Regnard2 reported that pressure inhibits bacterial movement. Subsequent studies3 confirmed and extended ...Type of Medium: Electronic ResourceURL: -
12Articles: DFG German National LicensesStaff View
ISSN: 1432-072XKeywords: Hydrogen cyanide biosynthesis ; Pseudomonas aeruginosa ; Phosphate effect on HCN ; Secondary metabolismSource: Springer Online Journal Archives 1860-2000Topics: BiologyNotes: Abstract The biosynthesis of hydrogen cyanide (HCN) by a strain of Pseudomonas aeruginosa is found to be significantly influenced by inorganic phosphate. Optimum HCN production occurs when the phosphate concentration is between 1 and 10 mM. Above and below this concentration the amount of HCN produced decreases sharply and at 0.1 and 100 mM phosphate low HCN production occurs. If a culture growing at 0.1 mM phosphate and producing low HCN is shifted to 10 mM phosphate, HCN biosynthesis resumes. Experiments with chloramphenicol indicate that de novo-protein synthesis is required for the process.Type of Medium: Electronic ResourceURL: -
13Articles: DFG German National LicensesStaff View
ISSN: 1432-0991Source: Springer Online Journal Archives 1860-2000Topics: BiologyMedicineNotes: Abstract Proteus mirabilis can grow anaerobically on the fermentable substrate, glucose. When the glucose medium was supplemented with an electron acceptor, growth doubled. However, the organism failed to grow anaerobically on the oxidizable substrate glycerol unless the medium was supplemented with an external electron acceptor. Dimethyl sulfoxide (DMSO), trimethylamine N-oxide (TMAO), nicotinamide N-oxide (NAMO), and nitrate (NO3) can serve this function. Cell-free extracts ofP. mirabilis can reduce these compounds in the presence of various electron donors. In order to determine whether the same or different terminal reductase(s) are involved in the reduction of these compounds, we isolated mutants unable to grow on glycerol/DMSO medium. When these mutants were tested on glycerol medium containing TMAO, NAMO, and NO3 as electron acceptors, it was found that there were two groups. Group I mutants were unable to grow with DMSO, TMAO, and NAMO, while their growth was unaffected with NO3. Group II mutants were unable to grow on any electron acceptor including NO3. Enzyme assays using reduced benzyl viologen with both groups of mutants were in agreement with growth studies. On the basis of these results, we conclude that the same terminal reductase is involved in the reduction of DMSO, TMAO, and NAMO (group I) and that the additional loss of NO3 reductase in group II mutants is probably owing to a defect in the synthesis or insertion of molybdenum cofactor.Type of Medium: Electronic ResourceURL: