EC Number   |
General Information |
Reference |
|---|
  1.14.13.101 | evolution |
during evolution, different insect lineages have developed specialized FMOs, pyrrolizidine alkaloid N-oxygenases (PNOs), as a counterstrategy to cope with pyrrolizidine alkaloids (PAs), which are toxic compounds that are produced by certain angiosperm species as part of their chemical defence against herbivores. PAs are produced by plants in their nontoxic polar N-oxide form. Isonzyme ZvPNO belongs to the flavin-dependent monooxygenases (FMOs), it is a member of class B (of six different FMO subclasses, A-F) within the family of flavin-dependent monooxygenases that originates from a more highly developed organism than yeast. Despite the differences in sequence between family members, their overall structure is very similar. PA N-oxygenases are the only functionally characterized FMOs found to date in insects |
763839 |
| 1.14.13.101 | more |
FMO isozymes' structure analysis and comparisons, overview. Based on initial docking experiments with the crystal structure of ZvPNO and different PA substrates, Tyr307 is identified as the most promising part of the binding pocket, potentially forming hydrogen bonds to a variety of PA substrates. Additionally, when comparing the crystal structures of ZvPNO with a homology model of ZvFMOa, a tyrosine residue (Tyr356) blocking the substrate entrance in the latter model is observed |
763839 |
| 1.14.13.101 | physiological function |
Zonocerus variegatus expresses three flavin-dependent monooxygenase (ZvFMO) isoforms, ZvFMOa, ZvFMOc and ZvPNO, which contribute to a counterstrategy against pyrrolizidine alkaloids (PAs). PAs are protoxic compounds produced by some angiosperm lineages as a chemical defence against herbivores. While ZvPNO is the most potent isoform, ZvFMOa and ZvFMOc show a specific activity that is 8-300fold lower, depending on the PA substrate. N-Oxygenation of PAs and the accumulation of PA N-oxides within their haemolymph result in two evolutionary advantages for these insects: (1) they circumvent the defence mechanism of their food plants and (2) they can use PA N-oxides to protect themselves against predators, which cannot cope with the toxic PAs. Despite a high degree of sequence identity and a similar substrate spectrum, the three ZvFMO isoforms differ greatly in enzyme activity. PA N-oxygenase (ZvPNO) is the most active ZvFMO isoform |
763839 |
| 1.14.13.101 | physiological function |
Zonocerus variegatus expresses three flavin-dependent monooxygenase (ZvFMO) isoforms, ZvFMOa, ZvFMOc and ZvPNO, which contribute to a counterstrategy against pyrrolizidine alkaloids (PAs). PAs are protoxic compounds produced by some angiosperm lineages as a chemical defence against herbivores. While ZvPNO is the most potent isoform, ZvFMOa and ZvFMOc show a specific activity that is 8-300fold lower, depending on the PA substrate. N-Oxygenation of PAs and the accumulation of PA N-oxides within their hemolymph result in two evolutionary advantages for these insects: (1) they circumvent the defence mechanism of their food plants and (2) they can use PA N-oxides to protect themselves against predators, which cannot cope with the toxic PAs. Despite a high degree of sequence identity and a similar substrate spectrum, the three ZvFMO isoforms differ greatly in enzyme activity. PA N-oxygenase (ZvPNO) is the most active ZvFMO isoform |
763839 |
