Eukaryotes express a multi-component fatty acid elongase to produce very long chain fatty acids (VLCFAs), which are building blocks of diverse lipids. Elongation is achieved by cyclical iteration of four reactions, the first of which generates a new carbon–carbon bond, elongating the acyl-chain. This reaction is catalyzed by either ELONGATION DEFECTIVE LIKE (ELO) or 3-ketoacyl-CoA synthase (KCS) enzymes. Whereas plants express both ELO and KCS enzymes, other eukaryotes express only ELOs. We explored the Zea mays KCS enzymatic redundancies by expressing each of the 26 isozymes in yeast strains that lacked endogenous ELO isozymes. Expression of the 26 maize KCS isozymes in wild-type, scelo2 or scelo3 single mutants did not affect VLCFA profiles. However, a complementation screen of each of the 26 KCS isozymes revealed five that were capable of complementing the synthetically lethal scelo2; scelo3 double mutant. These rescued strains express novel VLCFA profiles reflecting the different catalytic capabilities of the KCS isozymes. These novel strains offer a platform to explore the relationship between VLCFA profiles and cellular physiology.

真核生物表达多组分脂肪酸延长酶以产生超长链脂肪酸 (VLCFA)，它们是多种脂质的组成部分。伸长是通过四个反应的循环迭代来实现的，第一个反应产生一个新的碳-碳键，使酰基链伸长。该反应由 ELONGATION DEFECTIVE LIKE (ELO) 或 3-酮酰基-CoA 合酶 (KCS) 酶催化。植物同时表达 ELO 和 KCS 酶，而其他真核生物仅表达 ELO。我们通过在缺乏内源性 ELO 同工酶的酵母菌株中表达 26 种同工酶中的每一种来探索Zea mays KCS 酶冗余。26 种玉米 KCS 同工酶在野生型、scelo2或scelo3中的表达单个突变体不影响 VLCFA 谱。然而，对 26 种 KCS 同工酶中的每一种进行互补筛选后，发现有 5 种能够与合成致死的scelo2 互补。scelo3双突变体。这些获救的菌株表达了新的 VLCFA 谱，反映了 KCS 同工酶的不同催化能力。这些新菌株为探索 VLCFA 谱与细胞生理学之间的关系提供了一个平台。