生殖支原体GroEL蛋白的生物信息学分析、表达纯化及致炎分析

Bioinformatics, expression, purification, and inflammation-inducing effect of Mycoplasma genitalium GroEL protein

摘要:

为了解生殖支原体(Mycoplasma genitalium, Mg) GroEL蛋白的致病机制，本研究运用生物信息学软件对Mg GroEL蛋白结构和功能进行预测和分析，构建pET-28a-GroEL重组质粒，使用0.2 mmol/L IPTG诱导蛋白表达，通过Ni-亚氨基二乙酸(iminodicitic acid, IDA)柱亲和纯化获得Mg rGroEL蛋白。将浓度为2 μg/mL的Mg rGroEL蛋白作用于人单核细胞白血病THP-1细胞，通过ELISA检测细胞上清液中炎症因子IL-1β和TNF-α的含量，使用全自动化学发光仪检测细胞上清液中炎症因子IL-6的含量，通过细胞免疫荧光和Western blotting观察NF-κB信号通路激活情况。结果表明，Mg GroEL蛋白是含有543个氨基酸的酸性带负电荷蛋白，相对分子质量为58.44 kDa，等电点为5.68，分子式为C₂₅₆₈H₄₃₀₀N₇₀₀O₈₂₅S₈，为稳定的亲水性蛋白；二级结构以α-螺旋和无规则卷曲为主；Mg GroEL蛋白存在12个B细胞优势抗原表位和10个T细胞优势抗原表位。与肺炎支原体、无乳支原体、关节炎支原体、猪肺炎支原体和牛支原体的GroEL蛋白高度同源；Mg rGroEL蛋白能激活THP-1细胞NF-κB信号通路并促进IL-1β、IL-6和TNF-α的分泌。这些结果表明Mg GroEL具有较好的抗原性，能诱导宿主细胞发生炎症反应，本研究为进一步研究GroEL蛋白在Mg中的功能及其致病机制奠定了理论基础。

Abstract:

To preliminarily understand the pathogenic mechanism of Mycoplasma genitalium (Mg) GroEL protein, we used bioinformatics tools to predict the structure and function of Mg GroEL protein and then constructed the recombinant plasmid pET-28a-GroEL. The protein expression was induced by 0.2 mmol/L IPTG, and the expressed protein was purified by Ni-iminodicitic acid (IDA) column affinity. Tohoku Hospital Pediatrics-1 (THP-1) cells were exposed to 2 μg/mL Mg rGroEL. The levels of interleukin (IL)-1β and tumor necrosis factor (TNF)-α in the cell supernatant were measured by ELISA, and that of IL-6 was measured by an automatic chemiluminescence instrument. The activation of the nuclear factor-kappa B (NF-κB) signaling pathway was visualized by immunofluorescence and Western blotting. The results showed that Mg GroEL was a stable hydrophilic protein composed of 543 amino acid residues, with the relative molecular mass of 58.44 kDa, an isoelectric point of 5.68, and a molecular formula of C₂₅₆₈H₄₃₀₀N₇₀₀O₈₂₅S₈. The secondary structure was mainly composed of α-helices and random coils. Mg GroEL contained 12 B-cell dominant epitopes and 10 T-cell dominant epitopes. It exhibited high homology with the GroEL proteins from Mycoplasma pneumoniae, M. agalactiae, M. arthritidis, M. hyopneumoniae, and M. bovis. Mg rGroEL activated the NF-κB signaling pathway and promoted the secretion of IL-1β, IL-6, and TNF-α in THP-1 cells. These results suggest that Mg GroEL exhibits substantial antigenicity and possesses the capability of triggering inflammation in host cells. This study establishes a theoretical basis for future investigations pertaining to the role and pathogenic mechanisms of Mg GroEL.