Genetic Analysis of Polyunsaturated Fatty Acids Biosynthesis Pathway Determines Four Distinct Thraustochytrid Types

Area of Science:

• Marine microbiology
• Biochemistry
• Genomics

Background:

• Thraustochytrids are marine protists known for producing polyunsaturated fatty acids (PUFAs).
• PUFA synthesis occurs via PUFA synthase (PUFA-S) and/or elongase/desaturase (ELO/DES) pathways.
• Genetic distinctions underlying these pathways in thraustochytrids are not well understood.

Purpose of the Study:

• To investigate the genetic diversity of PUFA biosynthetic genes across thraustochytrid genera.
• To categorize thraustochytrid strains based on their PUFA biosynthetic gene complements.
• To explore the evolutionary implications of identified genetic variations.

Main Methods:

• Analysis of PUFA biosynthetic genes (PUFA-S, ELO/DES) in 19 thraustochytrid strains from six genera.
• Categorization of strains into four distinct types based on gene presence and absence.
• Synteny analysis to examine the genomic organization of these genes.

Main Results:

• Four distinct types of PUFA biosynthetic gene profiles were identified.
• Types I and II utilize ELO/DES pathways, with Type II also using PUFA-S; Types III and IV primarily use PUFA-S.
• Key enzymes like Δ9 desaturase and ATP-citrate lyase (ACLY) were found in Types I and II, while absent in Types III and IV, suggesting alternative metabolic strategies.

Conclusions:

• Significant genetic diversity exists in PUFA biosynthesis pathways among thraustochytrids.
• The study proposes four distinct evolutionary lineages for PUFA biosynthesis.
• Findings provide a foundation for understanding the evolution of PUFA production in these marine organisms.