大肠杆菌Nissle 1917鞭毛蛋白部分高变区功能初步研究

初步研究大肠杆菌Nissle 1917（E. coli Nissle 1917，EcN）鞭毛蛋白（Flagellin, FliC）高变区的功能，为探讨其作为表面展示系统的可行性打下基础。以EcN无质粒克隆（EcN was cured of its 2 cryptic plasmids pMUT1 and pMUT2 resulting in EcNc）为实验菌株，分别构建2个鞭毛蛋白基因（fliC）高变区859-888位、829-858位的缺失突变株和回补菌株。分析突变区域对EcNc的生长性能、生化特性、运动性及抗原性等方面的影响。结果显示：EcNc、两个缺失株和回补株的生长特性无明显差异，且三者生化试验结果一致。缺失突变株在半固体培养基上不能运动，而回补株均恢复了原运动性；缺失突变株均不与H1单因子血清发生凝集，而互补菌株均能产生与EcNc一致的凝集反应。表明高变区的这两个区域尽管不影响菌株的生长性能和生化特性，但与EcN的运动性及抗原性密切相关。这为进一步探索EcN鞭毛展示技术的研究提供了一定的数据。

PRELIMINARY STUDY ON THE FUNCTIONAL ROLE OF FLAGELLIN PARTIAL HYPERVARIABLE DOMAIN OF ESCHERICHIACOLI NISSLE 1917

The function of E. coli Nissle 1917 Flagellin partial hypervariable domain was investigated, it provided a basis for the potential approach of using E. coli Nissle 1917 Flagellin as a carrier for foreign peptides. We constructed two EcNc flagellin variants with deletions in the hypervariable domain 859-888 bp and 829-858 bp as well as their complemented strains. The bacterial growth, biochemical characteristics, motility and antigenicity were tested and analyzed. There were no apparent difference in growth rate and biochemical characteristics among EcNc,variants and complemented strains. Two variants exhibited abrogated motility, while the complementation strains restored the phenotype of EcNc, meanwhile, two variants lost substantial H antigenicity compared with both EcNc and complemented strains. EcNc flagellin variants with partial deletions of the hypervariable domain lose motility and antigenicity but did not influence growth rate and biochemical characteristics. These results provided an important experimental data and clues for exploration of peptide display on EcN flagella in the future.