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Oxylipin formation in Nostoc punctiforme (PCC73102)
1Georg-August-University of Göttingen, Albrecht-von-Haller-Institute of Plant Sciences, Department of Plant Biochemistry, Justus-von-Liebig-Weg 11, D-37085 Göttingen, Germany.
Phytochemistry
|April 7, 2007
Summary
Cyanobacteria possess lipoxygenases, enzymes previously thought to be plant-specific. These enzymes, like NpLOX1 in Nostoc punctiforme, produce signaling molecules involved in plant responses, and their activity increases upon wounding.
Area of Science:
- Biochemistry
- Plant Science
- Microbiology
Background:
- Lipoxygenases (LOX) catalyze polyunsaturated fatty acid dioxygenation, producing signaling molecules crucial for plant development and defense.
- While LOX pathways are well-studied in plants and mammals, their role in prokaryotes, particularly cyanobacteria, remains largely unexplored.
- Lipid peroxide metabolism is essential for cellular functions and responses to environmental stimuli.
Purpose of the Study:
- To investigate the presence and function of lipoxygenases in cyanobacteria.
- To analyze oxylipin patterns in Nostoc punctiforme and understand their metabolic relevance.
- To determine the substrate specificity and activity of cyanobacterial lipoxygenases.
Main Methods:
- Isolation and sequencing of lipoxygenase genes from Nostoc punctiforme PCC73102 DNA.
- Cloning and expression of lipoxygenase cDNAs (NpLOX1, NpLOX2) in E. coli.
- Biochemical characterization of NpLOX1, including pH optimum and substrate preference.
- Analysis of oxylipin profiles in wounded and non-wounded bacterial cells.
Main Results:
- Two lipoxygenase sequences, NpLOX1 and NpLOX2, were identified in Nostoc punctiforme.
- Both NpLOX1 and NpLOX2 were confirmed as linoleate 13-lipoxygenases.
- NpLOX1 exhibited a broad pH optimum (4.5-8.5, max at 8.0) and preferred alpha-linolenic acid.
- Wounding Nostoc punctiforme cells significantly increased 13-lipoxygenase-derived hydroperoxides, primarily non-esterified forms.
Conclusions:
- Cyanobacteria possess functional lipoxygenases, expanding the known phylogenetic distribution of these enzymes.
- 13-Lipoxygenase activity in Nostoc punctiforme is enhanced upon wounding, suggesting a role in stress response.
- The findings highlight the importance of lipid peroxide metabolism in cyanobacteria, similar to its role in plants.
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