为了探讨植物乳杆菌DMDL 9010胞外多糖合成蛋白cpsB的结构特性，该文通过生物信息学技术研究了胞外多糖合成蛋白cpsB的理化性质、亲/疏水性、跨膜结构、功能位点、磷酸化位点、信号肽、结构域、保守功能域、序列同源性以及空间结构进行预测与分析。结果表明胞外多糖合成蛋白cpsB相对分子质量约为2 920，等电点6.86，含有191个氨基酸；其为疏水蛋白，具有较高的稳定性；经过跨膜结构预测，发现其不存在跨膜结构，为胞内蛋白；胞外多糖合成蛋白cpsB中含有15个磷酸位点；氨基酸序列中不包含信号肽，所编码蛋白均为内分泌型蛋白；保守功能域预测中，基因中仅发现一段PHP 结构域，该基因可能参与调节胞外多糖的基因表达。胞外多糖合成蛋白cpsB的二级结构中α-螺旋占51.14%，并不存在β-折叠和β-转角结构，其三级结构比例与二级结构基本相似。该研究对植物乳杆菌DMDL 9010的胞外多糖合成蛋白cpsB功能机制进行深入研究，对利用基因工程技术研究其胞外多糖的生物合成具有重要意义。

To investigate the structural characteristics of cpsB, a capsular polysaccharide synthesis protein prepared with the help of Lactiplantibacillus plantarum DMDL 9010, the physical and chemical properties, hydrophilic/hydrophobic properties, transmembrane structure, functional sites, phosphorylation sites, signal peptides, structural domains, conserved functional domains, sequence homology, and spatial structure of cpsB were studied and predicted by bioinformatics. The results showed that the relative molecular weight of cpsB was 2 920, the isoelectric point was 6.86, and the protein contains 191 amino acids. It was a hydrophobic protein with high stability. The transmembrane structure prediction demonstrated that it has no transmembrane structure and it is an intracellular protein. CpsB contains 15 phosphate sites. The amino acid sequence does not contain signal peptides, and the encoded proteins are all endocrine proteins. In conserved functional domain prediction, only one PHP domain was found in the gene, which might be involved in regulating the expression of the exopolysaccharide gene. In the secondary structure of cpsB, α-helix accounts for 51.14%, and there are no β-sheets and β-turn structures. The proportion of tertiary structures in cpsB was similar to that of secondary structures. In this study, the functional mechanisms of cpsB, a capsular polysaccharide synthesis protein produced using Lactiplantibacillus plantarum DMDL 9010, were studied in depth. The findings are important to understand its extracellular polysaccharide biosynthesis through genetic engineering.

广东省基础与应用基础研究基金项目（2022A1515110426）；广东省科技创新战略专项资金（2022B1212010015）；佛山科学技术学院高层次人才经费（CGZ07001）；企业委托项目（BKH208034）