title: Analysis of Heme Biosynthetic Pathways in a Recombinant Escherichia coli.
abstract: Bacterial heme was produced from a genetic-engineered Escherichia coli via the porphyrin pathway and it was useful as an iron resource for animal feed. The amount of the E. colisynthesized heme, however, was only few milligrams in a culture broth and it was not enough for industrial applications. To analyze heme biosynthetic pathways, an engineered E. coli artificially overexpressing ALA synthase (hemA from Rhodobacter sphaeroides) and pantothenate kinase (coaA gene from self geneome) was constructed as a bacterial heme-producing strain, and both the transcription levels of pathway genes and the intermediates concentrations were determined from batch and continuous cultures. Transcription levels of the pathway genes were not significantly changed among the tested conditions. Intracellular intermediate concentrations indicated that aminolevulinic acid (ALA) and coenzyme A (CoA) were enhanced by the hemA-coaA co-expression. Intracellular coproporphyrinogen I and protoporphyrin IX accumulation suggested that the bottleneck steps in the heme biosynthetic pathway could be the spontaneous conversion of HMB to coproporphyrinogen I and the limited conversion of protoporphyrin IX to heme, respectively. A strategy to increase the conversion of ALA to heme is discussed based on the results.
authors.affiliation: Department of Biotechnology, the Catholic University of Korea, Bucheon 420-742, Republic of Korea.|Faculty of Biotechnology, Atma Jaya Catholic University of Indonesia, Jakarta Selatan 12930, Indonesia.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Pranawidjaja
authors.affiliation: Department of Biotechnology, the Catholic University of Korea, Bucheon 420-742, Republic of Korea.
authors.forename: Su-In
authors.initials: SI
authors.lastname: Choi
authors.affiliation: Faculty of Biotechnology, Atma Jaya Catholic University of Indonesia, Jakarta Selatan 12930, Indonesia.
authors.forename: Bibiana W
authors.initials: BW
authors.lastname: Lay
authors.affiliation: Department of Biotechnology, the Catholic University of Korea, Bucheon 420-742, Republic of Korea.
authors.forename: Pil
authors.initials: P
authors.lastname: Kim
mesh_terms: D053898:Biosynthetic Pathways / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism*; D020869:Gene Expression Profiling; D006418:Heme / Q000096:biosynthesis*; D060847:Metabolic Engineering / Q000379:methods*; D064688:Metabolic Flux Analysis
chemical_list: D006418:Heme