以植物乳杆菌P-8的基因组DNA为模板扩增出其羟基脂肪酸脱氢酶基因,对其进行生物信息学分析,结果表明该基因共编码286个氨基酸,蛋白质理论分子质量约为32 kDa,理论等电点为5.15,不含跨膜区,是1个亲水性的细胞质蛋白。Ser、Thr、Tyr磷酸化位点个数分别为3、3、7。蛋白质的二级结构主要构成方式为α螺旋、无规则卷曲和β折叠。将此基因连接到pET-28a(+)质粒载体中构建重组质粒pET28a-DH,并转化入大肠杆菌E.coli Transetta (DE3)中获得重组大肠杆菌。重组菌在16 ℃条件下,经0.1 mmol/L IPTG诱导16 h有可溶性表达,经Western Blot验证确定为重组羟基脂肪酸脱氢酶。通过镍柱亲和层析,得到纯化的重组酶。重组酶经初步活性检测,结果显示重组酶可以转化10-羟基-顺-12-十八碳烯酸为10-氧代-顺-12-十八碳烯酸,本研究为进一步探明植物乳杆菌P-8转化共轭亚油酸的机制奠定了基础。
The hydroxy fatty acid short chain dehydrogenase gene (CLA-DH) was amplified by PCR using the genomic DNA of Lactobacillus plantarum P-8 as a template. Bioinformatics analysis showed that this gene encoded 286 amino acids with a theoretical molecular mass of about 32 kDa, and a theoretical isoelectric point of 5.15. It was a hydrophilic cytoplasmic protein with no trans-membrane region. Its phosphorylation sites of serine, threonine, and tyrosine were 3, 3, and 7, respectively. The secondary structure of the protein mainly composed of α-helices, random coils, and β-sheets. The recombinant plasmid pET28a-DH was constructed by inserting CLA-DH into pET-28a(+), and then transformed into E.coli Transetta to obtain a compounded E.coli for expression. The recombinant bacteria had soluble expression at 16 ℃ after 16 h induction with 0.1 mmol/L IPTG. The results from Western Blot confirmed that the expression was recombinant CLA-DH. The purified recombinant CLA-DH was obtained by nickel column affinity chromatography. The preliminary activity assay of the recombinant CLA-DH showed that 10-hydroxy-cis-12-octadecenoic acid could be converted into 10-oxo-cis-12-octadecenoic acid, which laid a foundation for further analysis of the mechanism of transforming conjugated linoleic acid by L. plantarum P-8.
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