Ecobiomaterial Research Laboratory, School of Biological Sciences, Universiti Sains Malaysia, 11800 USM, Pulau Pinang, Malaysia.
Structural Biology Laboratory, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0192, Japan.
J Biosci Bioeng. 2022 Oct;134(4):288-294. doi: 10.1016/j.jbiosc.2022.07.005. Epub 2022 Aug 8.
Poly[(R)-3-hydroxybutyrate-co-(R)-3-hydroxyhexanoate] [P(3HB-co-3HHx)] has a high potential to serve as a commercial bioplastic due to its biodegradability, thermoplastic and mechanical properties. The properties of this copolymer are greatly affected by the composition of 3HHx monomer. One of the most efficient ways to modulate the composition of 3HHx monomer in P(3HB-co-3HHx) is by manipulating the (R)-3HHx-CoA monomer supply. In this study, a new (R)-specific enoyl-CoA hydratase originating from a non-PHA producer, Streptomyces sp. strain CFMR 7 (PhaJ), was characterized and found to be effective in supplying 3HHx monomer during in vivo production of P(3HB-co-3HHx) copolymer. The P(3HB-co-3HHx) copolymer produced from the Cupriavidus necator transformant that harbors phaJ, PHB4/pBBR1-CJ, showed enhanced 3HHx incorporation of up to 11 mol% without affecting the P(3HB-co-3HHx) production when palm oil was used as the carbon source. In addition, both k and k/K of PhaJ were higher toward the C6 than the shorter C4 substrates, underscoring the preference for 3-hydroxyhexanoyl-CoA. These results suggest that PhaJ has a significant ability to supply 3HHx monomers for PHA biosynthesis via β-oxidation and can be applied for metabolic engineering of robust PHA-producing strains.
聚[(R)-3-羟基丁酸酯-co-(R)-3-羟基己酸酯][P(3HB-co-3HHx)]由于其生物降解性、热塑性和机械性能,具有成为商业生物塑料的巨大潜力。该共聚物的性质受 3HHx 单体组成的影响很大。调节 P(3HB-co-3HHx)中 3HHx 单体组成的最有效方法之一是通过操纵(R)-3HHx-CoA 单体供应。在这项研究中,一种新型的(R)特异性烯酰-CoA 水合酶来源于非 PHA 产生菌,链霉菌 CFMR 7(PhaJ),并被证明在体内生产 P(3HB-co-3HHx)共聚物时有效供应 3HHx 单体。来自含有 phaJ 的铜绿假单胞菌转化体的 P(3HB-co-3HHx)共聚物,当使用棕榈油作为碳源时,PHA4/pBBR1-CJ 显示出高达 11mol%的 3HHx 掺入,而不影响 P(3HB-co-3HHx)的生产。此外,PhaJ 对 C6 底物的 k 和 k/K 均高于较短的 C4 底物,这表明其对 3-羟基己酰-CoA 的偏好。这些结果表明,PhaJ 通过β-氧化具有为 PHA 生物合成有效供应 3HHx 单体的能力,可用于生产稳健的 PHA 工程菌株的代谢工程。