title: Multiple propionyl coenzyme A-supplying pathways for production of the bioplastic poly(3-hydroxybutyrate-co-3-hydroxyvalerate) in Haloferax mediterranei.
abstract: Haloferax mediterranei is able to accumulate the bioplastic poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) with more than 10 mol% 3-hydroxyvalerate (3HV) from unrelated carbon sources. However, the pathways that produce propionyl coenzyme A (propionyl-CoA), an important precursor of 3HV monomer, have not yet been determined. Bioinformatic analysis of H. mediterranei genome indicated that this strain uses multiple pathways for propionyl-CoA biosynthesis, including the citramalate/2-oxobutyrate pathway, the aspartate/2-oxobutyrate pathway, the methylmalonyl-CoA pathway, and a novel 3-hydroxypropionate pathway. Cofeeding of pathway intermediates and inactivating pathway-specific genes supported that these four pathways were indeed involved in the biosynthesis of 3HV monomer. The novel 3-hydroxypropionate pathway that couples CO2 assimilation with PHBV biosynthesis was further confirmed by analysis of (13)C positional enrichment in 3HV. Notably, (13)C metabolic flux analysis showed that the citramalate/2-oxobutyrate pathway (53.0% flux) and the 3-hydroxypropionate pathway (30.6% flux) were the two main generators of propionyl-CoA from glucose. In addition, genetic perturbation on the transcriptome of the ΔphaEC mutant (deficient in PHBV accumulation) revealed that a considerable number of genes in the four propionyl-CoA synthetic pathways were significantly downregulated. We determined for the first time four propionyl-CoA-supplying pathways for PHBV production in haloarchaea, particularly including a new 3-hydroxypropionate pathway. These results would provide novel strategies for the production of PHBV with controllable 3HV molar fraction.
authors: State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.
authors: Jing
authors: J
authors: Han
authors: Jing
authors: J
authors: Hou
authors: Fan
authors: F
authors: Zhang
authors: Guomin
authors: G
authors: Ai
authors: Ming
authors: M
authors: Li
authors: Shuangfeng
authors: S
authors: Cai
authors: Hailong
authors: H
authors: Liu
authors: Lei
authors: L
authors: Wang
authors: Zejian
authors: Z
authors: Wang
authors: Siliang
authors: S
authors: Zhang
authors: Lei
authors: L
authors: Cai
authors: Dahe
authors: D
authors: Zhao
authors: Jian
authors: J
authors: Zhou
authors: Hua
authors: H
authors: Xiang
mesh_terms: D000214:Acyl Coenzyme A / Q000235:genetics / Q000378:metabolism*; D019843:Archaeal Proteins / Q000235:genetics / Q000378:metabolism; D053898:Biosynthetic Pathways; D057486:Carbon Cycle; D002245:Carbon Dioxide / Q000378:metabolism; D002247:Carbon Isotopes / Q000032:analysis; D019295:Computational Biology; D015536:Down-Regulation; D020869:Gene Expression Profiling; D019848:Gene Expression Regulation, Archaeal; D055786:Gene Knockout Techniques; D020745:Genome, Archaeal / Q000235:genetics*; D005947:Glucose / Q000378:metabolism; D019623:Haloferax mediterranei / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics; D009682:Magnetic Resonance Spectroscopy; D020411:Oligonucleotide Array Sequence Analysis; D010421:Pentanoic Acids / Q000378:metabolism*; D011091:Polyesters / Q000737:chemistry / Q000378:metabolism*; D020539:Sequence Analysis, Protein; D017384:Sequence Deletion; D000094122:Polyhydroxybutyrates
chemical_list: D000214:Acyl Coenzyme A; D019843:Archaeal Proteins; D002245:Carbon Dioxide; D002247:Carbon Isotopes; D005947:Glucose; D010421:Pentanoic Acids; D011091:Polyesters; C052620:poly(3-hydroxybutyrate)-co-(3-hydroxyvalerate); D000094122:Polyhydroxybutyrates; C013056:beta-hydroxyvaleric acid; C009061:propionyl-coenzyme A