KAS Genes for Fatty Acid Enrichment in Microalgae
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Solution Overview
Problem
Current methods for altering fatty acid profiles in cell oils produced by oleaginous microalgae are limited in their ability to enrich specific fatty acid content, such as C14:0, C8:0, and C10:0, which are desirable for various industrial applications.
Innovation Solution
The use of novel β-ketoacyl ACP synthase genes with at least 95% sequence identity to specific SEQ IDs, co-expressed with exogenous FATA or FATB acyl-ACP thioesterase genes in oleaginous microalgal host cells, to enhance the production of mid-chain and long-chain fatty acids, resulting in altered fatty acid profiles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional fatty acid biosynthesis pathways are used in oleaginous microalgae, then the natural fatty acid profile is maintained, but the ability to enrich specific fatty acids (C14:0, C8:0, C10:0) is limited
Solution Approach 1:
The fatty acid biosynthesis pathway is segmented into distinct enzymatic functions (KAS I-like enzymes for elongation, thioesterases for termination) that can be independently manipulated. By introducing specific KAS I-like genes (KASI, KASIV) and pairing them with specific thioesterases (FATA, FATB), the pathway is divided into controllable modules that produce specific fatty acid chain lengths, enabling enrichment of C14:0, C8:0, and C10:0 fatty acids
Solution Approach 2:
The invention changes key parameters of the biosynthetic pathway by introducing exogenous KAS I-like genes with specific substrate specificities (C2-C14 acyl-ACPs for KASI, similar for KASIV) and combining them with thioesterases having different chain length preferences. This parameter change in enzyme specificity enables precise control over fatty acid chain length distribution, achieving up to 55% C14:0 and 35% combined C8:0 and C10:0
2Manufacturing precision
If exogenous FAS genes are introduced to alter fatty acid profiles, then fatty acid composition can be modified, but the precision in achieving target enrichment levels (e.g., 55% C14:0) is insufficient
Solution Approach 1:
The invention uses universal KAS I-like enzyme components (KASI and KASIV) that can function across different microalgal hosts and can be paired with different thioesterase variants (FATA, FATB) to achieve multiple target fatty acid profiles. This modular universal system allows the same KAS gene to produce different fatty acid enrichment outcomes depending on which thioesterase partner is introduced, reducing the need for host-specific gene optimization
Solution Approach 2:
The invention employs feedback by systematically testing different combinations of KAS I-like genes with FATA and FATB thioesterases to determine which pairing achieves the desired fatty acid enrichment. The observed fatty acid profiles feed back into selecting the optimal gene combination, allowing precise achievement of target enrichment levels through iterative optimization
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly increases the levels of target fatty acids in cell oils, achieving enrichments of up to 55% C14:0 and 35% combined C8:0 and C10:0, exceeding the levels found in wild-type oils, and produces triglycerides suitable for food, chemical, and industrial uses.
Implementation Method 1
β-ketoacyl-ACP synthase I (KAS I, EC 2.3.1.41) is one of the enzymes responsible for elongation of growing medium-chain fatty acyl-ACP from 4 to 16 carbon atoms in length. KAS I uses C2-C14 acyl-ACPs as substrates for condensation with a C2 unit derived from malonyl-ACP.
Data Source
Figure 1
AI summary
The present invention relates to beta-ketoacyl ACP synthase genes of the KASI/KASIV type and proteins encoded by these genes. The genes can be included in nucleic acid constructs, vectors or host cells. Expression of the gene products can alter the fatty acid profile of host cells. The KAS genes can be combined with a FATA or FATB thioesterase gene to create a cell that produces an increased amount of C8-C16 fatty acids. Suitable host cells include plastidic cells of plants or microalgae. Oleaginous microalga host cells with the new genes are disclosed.