Z. Zheng1, Q. Gong1, M.-J. Zhang2, H.-L. Tian1, F.-F. Bei1, X.-J. Xue1,
and G.Q. Chen1,3,*
1 Dept. Biological Sciences and Biotechnology, Tsinghua University, Beijing 100084,China
2 Dept. Chemical and Materials Science, Beijing Institute of Technology, Beijing 100081, China
3 Multidisciplinary Research Center, Shantou University, Shantou, Guangdong 515063, China
Keywords: 3-hydroxydecanoic acid, (R)-3-hydroxydecanoyl-ACP-CoA transacylase, thioesterase II
3-Hydroxyalkanoic acids (3HA), as polyhydroxyalkanoates (PHA) monomer, may serve as intermediates for synthesis of many valuable chemicals, such as antibiotics, vitamins, aromatics, pheromones, and (S)-β-amino acids. 3HA monomers can be prepared either by chemical synthesis or by PHA degradation. In this presentation, the medium-chain-length 3HA—3-hydroxydecanoic acid (3HD) was directly bioproducing from non-related carbon source, such as glucose and fructose.
Recently, (R)-3-hydroxydecanoyl-acyl carrier protein-coenzyme A transacylase (PhaG), encoded by phaG gene was found to link fatty acid de novo biosynthesis to PHA production by converting 3HD-ACP to 3HD-CoA. Heterogenous expression of phaG isolated from Pseudomonas putida in Escherichia coli led to the extracellular production of 3-hydroxydecaoic acid (3HD) in a growth medium consisting of carbon source non-related to 3HD structure. By employing an isogenic tesB (encodes thioesterase II) negative knock-out E. coli strain CH01, it was found that the expression of tesB and phaG can up-regulate each other. In addition, 3HD was synthesized from glucose or fructose by recombinant E. coli harboring phaG and tesB. On the other hand, when the tesB gene was introduced into the polyhydroxyalkanoate synthase negative strain P. putida GPp104, extracellular 3HD producing by the recombinant strain was also observed. These results demonstrated that thioesterase II played an important role in 3HD production from non-related carbon source. It also supported the hypothesis that the physiological role of thioesterase II in E. coli was to prevent the abnormal accumulation of intracellular acyl-CoAs.
