Enzyme catalyzing Nitrogen Fixation in Bacteria Root nodules on legumes

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  • Slide 1
  • Enzyme catalyzing Nitrogen Fixation in Bacteria Root nodules on legumes
  • Slide 2
  • Nitrogenase is the enzyme found in a variety of bacteria, some of them symbiotic with plants catalyzes the conversion of molecular nitrogen (N 2 ) from the air into ammonia (NH 3 ). It is found in a variety of bacteria, some of them symbiotic with plants.
  • Slide 3
  • Diversity of N-fixing Bacteria
  • Slide 4
  • Choosing the sequence to compare Nitrogenase consists of a molybdenum-iron (MoFe) protein and an iron (Fe) protein. The MoFe protein contains 2 alpha protein chains and 2 beta protein chains.
  • Slide 5
  • Trials and Errors Constructed a phylogenetic tree of the Mo-Fe protein of nitrogenase from published nucleic acid data. Tried to get a more coherent tree by eliminating some of the sequences. Tree still not revealing. Mistake: using nucleotides, switched to amino acid sequences for the alpha and beta chains.
  • Slide 6
  • Amino Acid sequence Obtained amino acid sequence of alpha and beta subunits of MoFe protein from Azotobacter vinelandii Did an alignment on alpha and beta subunits and found 20.1% identity and, 78% global alignment, suggesting that alpha and beta chains are the product of gene duplication.
  • Slide 7
  • Crystallographic structure Found crystallographic structure for MoFe protein from A. vinelandii shown on next slide.
  • Slide 8
  • Structure Explorer - 1M34
  • Slide 9
  • Gene Duplication in the Mo-Fe Protein of Nitrogenase
  • Slide 10
  • Figure 54.18 The nitrogen cycle
  • Slide 11
  • Figure 37.9 The role of soil bacteria in the nitrogen nutrition of plants (Layer 3)
  • Slide 12
  • Figure 37.10 Root nodules on legumes
  • Slide 13
  • Figure 37.10x Nodules
  • Slide 14
  • Figure 37.11 Development of a soybean root nodule
  • Slide 15
  • Figure 37.13 Molecular biology of root nodule formation
  • Slide 16
  • Figure 37.12 Crop rotation and green manure
  • Slide 17
  • Figure 27.11 One of the most independent organisms on earth: Cyanobacteria (Anabaena)
  • Slide 18
  • Figure 27.11x1 Cyanobacteria: Gloeothece (top left), Nostoc (top right), Calothrix (bottom left), Fischerella (bottom right)
  • Slide 19
  • Figure 27.11x2 A bloom of cyanobacteria
  • Slide 20
  • Nutrient Deficiencies: Agricultural Importance Nitrogen deficiency
  • Slide 21
  • Figure 54.9 Nutrient addition experiments in a Hudson Bay salt marsh
  • Slide 22
  • Figure 27.8 Specialized membranes of prokaryotes