Engineering diverse fatty acid compositions of phospholipids in Escherichia coli
Engineering diverse fatty acid compositions of phospholipids in Escherichia coli
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DOI：
10.1016/j.ymben.2022.08.011
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发表时间：
2022-09-07
影响因子：
8.4
通讯作者：
Zhang, Fuzhong
中科院分区：
文献类型：
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作者：
Bai, Wenqin;Anthony, Winston E.;Zhang, Fuzhong
细菌脂肪酸（FAs）是细胞膜的重要组成部分，也是可再生化学物质的重要来源，因为它们可以转化为脂肪醇、酯类、酮类和烷烃，并被用作生物燃料、洗涤剂、润滑剂和商品化学品。大多数先前的FA生物转化是在羧酸基团上进行的。对FA烃链进行改性可以大大扩大FA衍生产品的结构和功能多样性。此外，这种修饰的FAs对其产生细胞的生长和代谢状态的影响尚不清楚。在这里，我们设计了新的大肠杆菌磷脂生物合成途径，创造了具有不同FA谱的菌株，富含o)7-不饱和FAs (o)7-UFAs, 75%)， A5-不饱和FAs (A5- ufas, 60%)，环丙烷FAs (CFAs, 55%)，内支链FAs （IBFAs, 40%）和A5，o)7-双不饱和FAs （DUFAs, 46%）。尽管在磷脂中具有截然不同的FA谱，但UFA、CFA和IBFA富集菌株显示出野生型样的表型谱和生长。转录组学分析显示，与UFA产生菌株相比，DUFA产生菌株增加了差异表达和诱导铁饥饿转录级联，但TCA周期激活率更高。这可能反映了DUFA生产的轻微成本，这导致在某些（但不是全部）环境条件下最大增长率较低。进一步设计IBFA富集菌株产生游离IBFA，从细胞总IBFA池的154 mg/L中释放出96 mg/L的游离IBFA。这项工作导致了大肠杆菌膜脂FA谱的显著改变，极大地增加了我们对FA结构多样性对转录组、生长和应激反应能力的影响的理解。
Bacterial fatty acids (FAs) are an essential component of the cellular membrane and are an important source of renewable chemicals as they can be converted to fatty alcohols, esters, ketones, and alkanes, and used as biofuels, detergents, lubricants, and commodity chemicals. Most prior FA bioconversions have been performed on the carboxylic acid group. Modification of the FA hydrocarbon chain could substantially expand the structural and functional diversity of FA-derived products. Additionally, the effects of such modified FAs on the growth and metabolic state of their producing cells are not well understood. Here we engineer novel Escherichia coli phospholipid biosynthetic pathways, creating strains with distinct FA profiles enriched in o)7-unsaturated FAs (o)7-UFAs, 75%), A5-unsaturated FAs (A5-UFAs, 60%), cyclopropane FAs (CFAs, 55%), internally-branched FAs (IBFAs, 40%), and A5,o)7-double unsaturated FAs (DUFAs, 46%). Although bearing drastically different FA profiles in phospholipids, UFA, CFA, and IBFA enriched strains display wild-type-like phenotypic profiling and growth. Transcriptomic analysis reveals DUFA production drives increased differential expression and the induction of the fur iron starvation transcriptional cascade, but higher TCA cycle activation compared to the UFA producing strain. This likely reflects a slight cost imparted for DUFA production, which resulted in lower maximum growth in some, but not all, environmental conditions. The IBFA-enriched strain was further engineered to produce free IBFAs, releasing 96 mg/L free IBFAs from 154 mg/L of the total cellular IBFA pool. This work has resulted in significantly altered FA profiles of membrane lipids in E. coli, greatly increasing our understanding of the effects of FA structure diversity on the transcriptome, growth, and ability to react to stress.