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Cyanophage-encoded lipid desaturases: oceanic distribution, diversity and function
Sheila Roitman1, Ellen Hornung2, José Flores-Uribe1
1Faculty of Biology, Technion-Israel Institute of Technology, Haifa, Israel.
The ISME Journal
|October 14, 2017
Summary
Cyanophages, viruses that infect cyanobacteria, possess a novel auxiliary metabolic gene encoding a fatty acid desaturase (FAD). This viral FAD enzyme modifies host cell membranes, potentially enhancing photoprotection and viral fitness.
Area of Science:
- Marine microbiology
- Virology
- Biochemistry
Background:
- Cyanobacteria are abundant marine photosynthetic organisms.
- Cyanophages (viruses infecting cyanobacteria) impact marine ecosystems and biogeochemical cycles.
- Cyanophages utilize auxiliary metabolic genes (AMGs) to enhance their fitness by altering host cell metabolism.
Purpose of the Study:
- To identify and characterize novel auxiliary metabolic genes (AMGs) in cyanophages.
- To investigate the function of a newly discovered viral fatty acid desaturase (vFAD) in cyanophage-host interactions.
- To understand the role of vFAD in host membrane modification and stress response.
Main Methods:
- Genomic analysis to identify viral AMGs.
- Biochemical assays to determine vFAD activity (Δ9 desaturase).
- Comprehensive fatty acid profiling of marine cyanobacteria.
Main Results:
- A novel, widespread cyanophage AMG encoding a fatty acid desaturase (FAD) was identified in two distinct genotypes.
- Both viral FAD (vFAD) families function as Δ9 lipid desaturases, catalyzing desaturation at carbon 9 of C16 fatty acids.
- Marine cyanobacteria exhibit a unique desaturation pathway for medium- to long-chain fatty acids up to C16, consistent with vFAD activity.
Conclusions:
- Cyanophages encode FADs that modify host cell membrane fluidity.
- This modification may enhance photoprotection for the host and potentially benefit viral fitness.
- Cyanophages can establish a novel viral metabolic network by manipulating host membrane properties.