Journal News

JLR: How a single-cell marine organism makes fatty acids

Courtney Chandler
November 01, 2016

Omega-3 fatty acids have been heralded as crucial to our health and well-being. Humans and other mammals cannot synthesize these fatty acids on their own. Organisms capable of synthesizing these important molecules, such as a single-celled marine organism called Thraustochytrium, are of interest for their use as dietary supplements. In a recent paper published in the Journal of Lipid Research, Dauenpen Meesapyodsuk and Xiao Qiu of the University of Saskatchewan in Canada report the pathway that is responsible for the synthesis of these fatty acids in Thraustochytrium.

Omega-3

Omega-3 fatty acids, which can be categorized as very long chain polyunsaturated fatty acids, known as VLCPUFAs, are important components of cell membranes. They also form products that are involved in blood circulation, metabolism, neurotransmission and inflammation. Mammals can obtain omega-3 fatty acids from foods such as salmon and walnuts or from dietary supplements.

Thraustochytrium has been used as a commercial source for these healthy fatty acids. Scientists knew that these organisms produced large quantities of VLCPUFAs but didn’t know exactly how they did it.

Organisms are thought to synthesize VLCPUFAs through two possible pathways. The first is the aerobic pathway. It requires oxygen and involves lengthening and adding double bonds to existing fatty acid intermediates. The second is the anaerobic pathway. It does not require oxygen and uses specific enzymes to build VLCPUFAs directly from small precursor molecules, such as acetate.

Qiu’s laboratory previously had demonstrated the presence of an enzyme involved in the aerobic pathway in a species of Thraustochytrium called Thraustochytrium sp. 26185. They also recently had observed the coexistence of the anaerobic pathway in the same organism. “This prompted us to investigate the function and importance of the two pathways for the biosynthesis of VLCPUFAs in the species,” explains Qiu.

Qiu and Meesapyodsuk investigated the pathways by analyzing the important genes of each in E. coli or yeast, which essentially served as a blank slate to isolate the Thraustochytrium genes and examine their function. They used gas chromatography coupled to mass spectrometry to analyze fatty acid structure; they used feeding experiments to track VLCPUFA formation.

The data “show that the anaerobic pathway is responsible for the VLCPUFA biosynthesis in the Thraustochytrium,” states Qiu. Thraustochytrium uses enzymes to build the VLCPUFAs sequentially from a small base molecule instead of making modifications to existing PUFAs.

What about the aerobic synthesis pathway that also was shown to be present in the same species? “Although both aerobic and anaerobic pathways for biosynthesis coexist in the Thraustochytrium, the aerobic pathway is not complete,” explains Qiu. This pathway has several enzymes that are ineffective. This makes it incapable of generating VLCPUFAs.

There is a simple explanation for why both pathways may exist in a species — evolution. “It is believed that the aerobic pathway is a progenitor system, while the anaerobic pathway is later acquired by the species,” explains Qiu. The anaerobic pathway is more efficient at producing VLCPUFAs. As time went on, components of the less effective aerobic pathway could have become unnecessary and been lost.

VLCPUFAs are important for our health, so it is important to understand how they are produced in the organisms we rely on to supplement our diets. This knowledge could in turn help engineer similar systems that produce VLCPUFAs. Qiu says, “Metabolic engineering of VLCPUFAs in heterologous systems (could) provide an alternative source of these fatty acids for human and animal consumption.”

Courtney Chandler

Courtney Chandler is a postdoctoral researcher at the Department of Biochemistry and Molecular Biology at the Johns Hopkins University School of Public Health and an industry careers columnist for ASBMB Today.

Join the ASBMB Today mailing list

Sign up to get updates on articles, interviews and events.

Latest in Science

Science highlights or most popular articles

Lessons from how the polio vaccine
News

Lessons from how the polio vaccine

September 26, 2020

Despite the polio vaccine’s long-term success, manufacturers, government leaders and the nonprofit that funded the vaccine’s development made several missteps.

From the journals: MCP
Journal News

From the journals: MCP

September 25, 2020

How marine iguanas mark their turf. A new way to study Parkinson’s disease. Glycosylation in influenza A. Read about recent papers on these topics in the journal Molecular & Cellular Proteomics.

Gut microbiome shaped by dietary sphingolipids
Journal News

Gut microbiome shaped by dietary sphingolipids

September 22, 2020

A new tracing method described in the Journal of Lipid Research offers clues on how a macronutrient interacts with the microbes that live inside us.

From the journals: JBC
Journal News

From the journals: JBC

September 21, 2020

Proteases that fire up the flu. A sulfate pocket to take out MRSA. Proteins that prompt cancer protrusions. Read about recent papers on these topics and more.

AeroNabs promise powerful, inhalable protection against COVID-19
News

AeroNabs promise powerful, inhalable protection against COVID-19

September 20, 2020

As the world awaits vaccines to bring the COVID-19 pandemic under control, UC San Francisco scientists have devised a novel approach to halting the spread of SARS-CoV-2, the virus that causes the disease.

Keeping bone and muscle strong on the ISS
News

Keeping bone and muscle strong on the ISS

September 19, 2020

Researchers helped mice stay mighty with an experiment to counter the effects of microgravity. The gene treatment might also enhance muscle and bone health on Earth — and in humans.