Production of hydroxy fatty acids and its effects on photosynthesis in the cyanobacterium Synechocystis sp. PCC 6803.
Production of hydroxy fatty acids and its effects on photosynthesis in the cyanobacterium Synechocystis sp. PCC 6803.
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蓝藻集胞藻中羟基脂肪酸的产生及其对光合作用的影响。
DOI：
10.1016/j.algal.2020.102155
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发表时间：
2021
期刊：
影响因子：
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通讯作者：
Awai K and Suzuki I
中科院分区：
文献类型：
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作者：
Inada T;Machida S;Awai K and Suzuki I
微藻油脂和脂肪酸是实现生物燃料的重要组成部分，因为它们具有潜在的高生产力。为了从3-羟基丁基-CoA生产（ω-1）-羟基脂肪酸，3-羟基丁基-CoA是蓝细菌Synechocystis sp. PCC 6803中多羟基丁酸生物合成的中间体，我们通过pc 560启动子表达了来自酸热脂环酸杆菌的混杂3-酮脂酰-ACP合酶III（aaKASIII）的基因。为了提供aaKASIII所需的3-羟基丁酰辅酶A，删除了多羟基丁酸聚合酶的phaC基因，并过量表达了钩虫贪铜菌合成3-羟基丁酰辅酶A的phaAB基因。转基因菌株合成15-羟基十六烷酸、17-羟基十八烷酸和17-羟基十八碳-9-烯酸，在70 μmol光子m−2s−1的光照下，总脂肪酸中积累了约2.1 mol%的（ω−1）-羟基脂肪酸，尽管其生长严重受阻。在弱光（35 μmol光子m−2s−1）条件下，菌株生长与野生型一样，羟基脂肪酸（0.04 mol%）积累低于较高光照水平。该菌株的光合活性低于野生型细胞，表明强光条件下增强羟基脂肪酸的生产，抑制光合作用。（ω−1）-羟基脂肪酸在薄层色谱法的半乳糖脂中没有主要观察到，而半乳糖脂是蓝细菌中的主要脂类。据我们所知，这是第一次报告光合自养生产的脂肪酸拥有一个功能团附近的末端的酰基链在蓝藻。
Microalgal lipids and fatty acids are important components for achieving biofuel because of their potential high productivity. Although fatty acids that have a hydroxy group adjacent to the end of the acyl chain might be an important chemical feedstock, most algae do not accumulate it. To produce (ω−1)-hydroxy fatty acids from 3-hydroxybutylyl-CoA, an intermediate for polyhydroxybutylate biosynthesis in the cyanobacterium Synechocystis sp. PCC 6803, we expressed a gene for the promiscuous 3-ketoacyl-ACP synthase III from Alicyclobacillusacidocalderius(aaKASIII) by thecpc560promoter. To supply 3-hydroxybutyryl-CoAs for aaKASIII, thephaCgene for polyhydroxybutylate polymerase was deleted, and thephaABgenes for 3-hydroxybutyryl-CoA synthesis from Cupriavidus necator were overexpressed. The genetically modified strain synthesized 15-hydroxyhexadecanoic acid, 17-hydroxyoctadecanoic acid, and 17-hydroxyoctadec-9-enoic acid, and accumulated approximately 2.1 mol% of (ω−1)-hydroxy fatty acids in total fatty acids under illumination with 70 μmol photons m−2s−1, although its growth was severely retarded. Under weak light (35 μmol photons m−2s−1) conditions, the strain grew as well as the wild-type and showed lower hydroxy fatty acids (0.04 mol%) accumulation than that at higher illumination levels. The photosynthetic activity of this strain was lower than that of wild-type cells, suggesting that high light conditions enhanced hydroxy fatty acids production and inhibited photosynthesis. (ω−1)-Hydroxy fatty acids were not predominantly observed in the galactolipids from thin-layer chromatography, which are the major lipid classes in cyanobacteria. To the best of our knowledge, this is the first report on photoautotrophic production of fatty acids possessing a functional group near the end of the acyl chain in cyanobacteria.