title: A novel MVA-mediated pathway for isoprene production in engineered E. coli.
abstract: BACKGROUND
  To deal with the increasingly severe energy crisis and environmental consequences, biofuels and biochemicals generated from renewable resources could serve as a promising alternative for replacing petroleum as a source of fuel and chemicals, among which isoprene (2-methyl-1,3-butadiene) in particular is of great significance in that it is an important platform chemical, which has been used in industrial production of synthetic rubber for tires and coatings or aviation fuel.
  
  
  RESULTS
  We firstly introduced fatty acid decarboxylase (OleTJE) from Jeotgalicoccus species into E. coli to directly convert MVA(mevalonate) into 3-methy-3-buten-1-ol. And then to transform 3-methy-3-buten-1-ol to isoprene, oleate hydratase (OhyAEM) from Elizabethkingia meningoseptica was overexpressed in E. coli. A novel biosynthetic pathway of isoprene in E. coli was established by co-expressing the heterologous mvaE gene encoding acetyl-CoA acetyltransferase/HMG-CoA reductase and mvaS gene encoding HMG-CoA synthase from Enterococcus faecalis, fatty acid decarboxylase (OleTJE) and oleate hydratase (OhyAEM). Furthermore, to enhance isoprene production, a further optimization of expression level of OleTJE, OhyAEM was carried out by using different promoters and copy numbers of plasmids. Thereafter, the fermentation process was also optimized to improve the production of isoprene. The final engineered strain, YJM33, bearing the innovative biosynthetic pathway of isoprene, was found to produce isoprene up to 2.2 mg/L and 620 mg/L under flask and fed-batch fermentation conditions, respectively.
  
  
  CONCLUSIONS
  In this study, by using metabolic engineering techniques, the novel MVA-mediated biosynthetic pathway of isoprene was successfully assembled in E. coli BL21(DE3) with the heterologous MVA upper pathway, OleTJE from Jeotgalicoccus species and OhyAEM from Elizabethkingia meningoseptica. Compared with traditional MVA pathway, the novel pathway is shortened by 3 steps. In addition, this is the first report on the reaction of converting MVA into 3-methy-3-buten-1-ol by fatty acid decarboxylase (OleTJE) from Jeotgalicoccus species. In brief, this study provided an alternative method for isoprene biosynthesis, which is largely different from the well-developed MEP pathway or MVA pathway.
authors.affiliation: CAS Key Laboratory of Biobased Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101, China. yjming888@126.com.|Key Lab of Applied Mycology, College of Life Sciences, Qingdao Agricultural University, Qingdao, 266109, China. yjming888@126.com.
authors.forename: Jianming
authors.initials: J
authors.lastname: Yang
authors.affiliation: Foreign Languages School, Qingdao Agricultural University, Qingdao, 266109, China. nieqingjuan@163.com.
authors.forename: Qingjuan
authors.initials: Q
authors.lastname: Nie
authors.affiliation: CAS Key Laboratory of Biobased Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101, China. liuhui@qibebt.ac.cn.
authors.forename: Hui
authors.initials: H
authors.lastname: Liu
authors.affiliation: CAS Key Laboratory of Biobased Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101, China. xianmo@qibebt.ac.cn.
authors.forename: Mo
authors.initials: M
authors.lastname: Xian
authors.affiliation: CAS Key Laboratory of Biobased Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101, China. liuhuizhou@qibebt.ac.cn.
authors.forename: Huizhou
authors.initials: H
authors.lastname: Liu
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D002070:Butadienes / Q000032:analysis / Q000378:metabolism*; D002262:Carboxy-Lyases / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism*; D005285:Fermentation; D045782:Hemiterpenes / Q000032:analysis / Q000378:metabolism*; D006904:Hydroxymethylglutaryl-CoA Synthase / Q000235:genetics / Q000378:metabolism; D060847:Metabolic Engineering / Q000379:methods*; D053858:Metabolic Networks and Pathways / Q000235:genetics; D008798:Mevalonic Acid / Q000378:metabolism*; D010420:Pentanes / Q000032:analysis / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D002070:Butadienes; D045782:Hemiterpenes; D010420:Pentanes; C005059:isoprene; D006904:Hydroxymethylglutaryl-CoA Synthase; D002262:Carboxy-Lyases; D008798:Mevalonic Acid