title: Effect of cerulenin on fatty acid composition and gene expression pattern of DHA-producing strain Colwellia psychrerythraea strain 34H.
abstract: BACKGROUND
  Colwellia psychrerythraea 34H is a psychrophilic bacterium able to produce docosahexaenoic acid (DHA). Polyketide synthase pathway is assumed to be responsible for DHA production in marine bacteria.
  
  
  RESULTS
  Five pfa genes from strain 34H were confirmed to be responsible for DHA formation by heterogeneous expression in Escherichia coli. The complexity of fatty acid profile of this strain was revealed by GC and GC-MS. Treatment of cells with cerulenin resulted in significantly reduced level of C16 monounsaturated fatty acid (C16:1(Δ9t), C16:1(Δ7)). In contrast, the amount of saturated fatty acids (C10:0, C12:0, C14:0), hydroxyl fatty acids (3-OH C10:0 and 3-OH C12:0), as well as C20:4ω3, C20:5ω3 and C22:6ω3 were increased. RNA sequencing (RNA-Seq) revealed the altered gene expression pattern when C. psychrerythraea cells were treated with cerulenin. Genes involved in polyketide synthase pathway and fatty acid biosynthesis pathway were not obviously affected by cerulenin treatment. In contrast, several genes involved in fatty acid degradation or β-oxidation pathway were dramatically reduced at the transcriptional level.
  
  
  CONCLUSIONS
  Genes responsible for DHA formation in C. psychrerythraea was first cloned and characterized. We revealed the complexity of fatty acid profile in this DHA-producing strain. Cerulenin could substantially change the fatty acid composition by affecting the fatty acid degradation at transcriptional level. Acyl-CoA dehydrogenase gene family involved in the first step of β-oxidation pathway may be important to the selectivity of degraded fatty acids. In addition, inhibition of FabB protein by cerulenin may lead to the accumulation of malonyl-CoA, which is the substrate for DHA formation.
authors: Key Laboratory of Biology and Genetic Improvement of Oil Crops, Ministry of Agriculture, Oil Crops Research Institute of Chinese Academy of Agricultural Sciences, Wuhan, 430062, China. wanxia@oilcrops.cn.|Hubei Key Laboratory of Lipid Chemistry and Nutrition, Wuhan, 430062, China. wanxia@oilcrops.cn.
authors: Xia
authors: X
authors: Wan
authors: Key Laboratory of Biology and Genetic Improvement of Oil Crops, Ministry of Agriculture, Oil Crops Research Institute of Chinese Academy of Agricultural Sciences, Wuhan, 430062, China. 1171418260@qq.com.
authors: Yun-Feng
authors: YF
authors: Peng
authors: CSIRO Agriculture, Canberra, ACT, 2601, Australia. Xue-Rong.Zhou@csiro.au.|CSIRO Food and Nutrition, Canberra, ACT, 2601, Australia. Xue-Rong.Zhou@csiro.au.
authors: Xue-Rong
authors: XR
authors: Zhou
authors: Key Laboratory of Biology and Genetic Improvement of Oil Crops, Ministry of Agriculture, Oil Crops Research Institute of Chinese Academy of Agricultural Sciences, Wuhan, 430062, China. gongym@oilcrops.cn.
authors: Yang-Min
authors: YM
authors: Gong
authors: Key Laboratory of Biology and Genetic Improvement of Oil Crops, Ministry of Agriculture, Oil Crops Research Institute of Chinese Academy of Agricultural Sciences, Wuhan, 430062, China. huangfh@oilcrops.cn.|Hubei Key Laboratory of Lipid Chemistry and Nutrition, Wuhan, 430062, China. huangfh@oilcrops.cn.
authors: Feng-Hong
authors: FH
authors: Huang
authors: Departamento de Biología Molecular e Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), Universidad de Cantabria-CSIC, C/Albert Einstein 22, 39011, Santander, Spain. gabriel.moncalian@unican.es.
authors: Gabriel
authors: G
authors: Moncalián
mesh_terms: D034241:Alteromonadaceae / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development; D053898:Biosynthetic Pathways / Q000187:drug effects; D002569:Cerulenin / Q000494:pharmacology*; D002849:Chromatography, Gas; D004281:Docosahexaenoic Acids / Q000096:biosynthesis*; D004952:Esters / Q000378:metabolism; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects*; D005798:Genes, Bacterial; D006900:Hydroxylation; D058977:Molecular Sequence Annotation; D015203:Reproducibility of Results; D013696:Temperature; D059467:Transcriptome / Q000187:drug effects / Q000235:genetics; D015854:Up-Regulation / Q000187:drug effects / Q000235:genetics
chemical_list: D004952:Esters; D002569:Cerulenin; D004281:Docosahexaenoic Acids