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Showing 1 to 20 of 31 for “"Azotobacter vinelandii"”.
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Mutagenesis of nifE and nifN from Azotobacter vinelandii
The products of nifE and nifN from Azotobacter vinelandii, which are involved in the biosynthesis of the iron-molybdenum cofactor (FeMo-co) co) from nitrogenase, have been analyzed using a variety of mutagenic techniques. NifE was the object of several site-specific, amino acid substitutions that …
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Characterization and site-directed mutagenesis of NifU from Azotobacter vinelandii
… nifU gene product in nitrogenase maturation in Azotobacter vinelandii. the gene product has been hyperexpressed in Escherichia coli and characterized by various biophysical techniques. Following the initial characterization, site-directed mutagenesis of conserved cysteinyl residues was performed …
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Site-directed mutagenesis of the nitrogenase MoFe protein from Azotobacter vinelandii
… the four 4Fe-4S centers (P-clusters) within the Azotobacter vinelandii nitrogenase MoFe protein is presented. Based on interspecies and intersubunit amino acid comparisons of the α- and ß-subunits of the MoFe protein, and the FeMoco biosynthetic proteins, NifE and NifN, four conserved residues …
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Aislamiento y caracterización de mutantes del metabolismo del nitrogeno en "Azotobacter vinelandii"
… la regulación del metabolismo del nitrógeno en Azotobacter vivelandii es de gran interés debido a su posible utilización con fines prácticos. En esta tesis se aborda el estudio de esta regulación estableciendo la existencia características
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Characterization of an altered MoFe protein from a nifV- strain from Azotobacter vinelandii
… encoded by nifV. By deleting the nifV gene from Azotobacter vinelandii we were able to study the role of homocitrate in nitrogenase catalysis. A poly-histidine tail was incorporated into the C-termini of the a-subunit permitting isolation of the homocitrateless MoFe protein by using metal …
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Natural transformation and growth inhibition of azotobacter vinelandii in the presence of adsorbed oxytetracycline
… and inhibition of the soil bacterium Azotobacter vinelandii was investigated. The transformation frequency by both plasmid and chromosomal DNA was not significantly affected by the addition of adsorbed OTC, showing that the presence of OTC does not hinder gene transfer. A higher …
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Azotobacter vinelandii nitrogenase: role of the MoFe protein α-subunit histidine-195 residue in catalysis
… were used to isolate mutant strains of <i>Azotobacter vinelandii</i> that produce altered MoFe proteins where the α-subunit residue-195 position, normally occupied by a histidine residue, was individually substituted by a variety of other amino acids. Structural studies have revealed that …
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Genetic analysis of nifF and nifA and site-directed mutagenesis of nifE in Azotobacter vinelandii
… nifE (FeMo-cofactor biosynthesis) genes from <i>Azotobacter vinelandii</i> were genetically analyzed. The nucleotide sequence of the nifF gene, which encodes a flavodoxin, was determined. Specific mutation strains indicated that in <i>A vinelandii</i> flavodoxin is not the unique physiological …
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Controlled Expression and Functional Analysis of the Iron-Sulfur Cluster Biosynthetic Machinery in Azotobacter vinelandii
… for the controlled expression of genes in Azotobacter vinelandii by using genomic fusions to the sucrose catabolic regulon. This system was used for the functional analysis of the A. vinelandii isc genes, whose products are involved in the maturation of [Fe-S] proteins. For this analysis …
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Azotobacter vinelandii Nitrogenase: Multiple Substrate-Reduction Sites and Effects of pH on Substrate Reduction and CO Inhibition
… J et al., 1997). Altered MoFe proteins of A. vinelandii nitrogenase, with the a278Thr, a278Cys, a278Ala and a278Leu substitutions, were used to study the interactions of H+, C2H2, N2 and CO with the enzyme. All strains, except the a278Leu mutant strain, were Nif+. From measurement of the Km …
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Role of the MoFe Protein β-95-Cysteinyl Residue in Nitrogenase Catalysis in <i>Azotobacter vinelandii</i>
… subtle changes were introduced at β-95-Cys in <i>Azotobacter vinelandii</I>nitrogenase through site-directed mutagenesis and gene replacement method. Some crude extracts from the mutants with substitutions at β-Cys contain typical FeMo cofactor EPR signal. The β-95<sup>Asp</sup> MoFe protein also …
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Biosynthesis of the Nitrogenase FeMo-cofactor from Azotobacter vinelandii: Involvement of the NifEN complex, NifX and the Fe protein
… protein produced by a nifB-deletion mutant of A. vinelandii. Using the poly-histidine fusion approach, apo-MoFe protein was obtained in sufficient quantities for detailed catalytic, kinetic and spectroscopic analyses. This multidisciplinary approach confirmed that apo-MoFe protein contained intact …
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The P Cluster of the Azotobacter vinelandii Nitrogenase Complex: Effects of Substitution at the Cluster-bridging Residue, a-Cys88
… solution of the x-ray crystal structure of the Azotobacter vinelandii MoFe protein, it was had been determined which of the highly conserved cysteinyl residues of this protein were likely P cluster ligands. After elucidation of the crystal structure, it became evident that cysteine-88 of the …
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Roles of MoFe protein α-274-histidine, α-276-tyrosine and α-277-arginine residues in Azotobacter vinelandii nitrogenase catalysis
… method at α-274-His, α-276-Tyr and α-277-Arg in Azotobacter vinelandii nitrogenase. Characterization of mutants strains resulting from amino acid substitutions at residues, α-274-His, α-276-Tyr or α-277-Arg, using activity assays, resulted in mixed Nif phenotypes. Therefore, none of these …
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Studies on the structure and function of various nif and nif- associated gene products encoded within the Azotobacter vinelandii nif gene cluster
… within the MoFe protein of nitrogenase from Azotobacter vinelandii. A gene replacement strategy was developed for oligonucleotide-directed mutagenesis of these proteins and the resulting biological and biochemical effects of these changes were examined. Identification of structurally …
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Azotobacter vinelandii Nitrogenase: Effect of Amino-Acid Substitutions at the Alpha Gln-191 Residue of the MoFe Protein on Substrate Reduction and CO Inhibition
… in the Alpha-subunit of the MoFe protein of A. vinelandii nitrogenase was targeted for substitution because its side chain is involved in a hydrogen-bond network from one of the terminal carboxylates of the homocitrate component of FeMo cofactor through to the backbone NH of Alpha Gly-61, which …
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Development of a cell flux model and its application to nitrogen fixers
… We have tested the model using data from Azotobacter vinelandii grown in continuous culture. The model indicates that the direct energy cost of nitrogen fixation is relatively small, whereas oxygen management to protect nitrogenase becomes dominant as the oxygen concentration increases. In …
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Protein Specificity Dictates Proper Sulfur Transfer in the Biosynthesis of Thio-cofactors in Bacteria
… cysteine desulfurases from Bacillus subtilis and Azotobacter vinelandii. Despite differences in biosynthetic schemes, these pathways are controlled by specific and dynamic protein-protein interactions and dependent on the availability of reaction components including cysteine and reducing …
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Atomic Force Microscope Conductivity Measurements of Single Ferritin Molecules
… of single horse spleen ferritin (HoSF) and azotobacter vinelandii bacterial ferritin (AvBF) molecules deposited on flat gold surfaces. A 500 micron diameter gold ball was also used as a contact probe to measure the conductivity of a thin film of ferritin molecules. The average current …
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