核桃细菌性黑斑病菌分泌蛋白质的理化性质及特征分析

Physicochemical properties and characteristic analysis of secretory proteins in walnut bacterial black spot pathogen

核桃细菌性黑斑病严重影响着核桃的产量和品质,是核桃生产过程中危害较为严重的病害之一。植物病原真菌、细菌以及卵菌的分泌蛋白质在其致病过程中发挥着重要的作用。本研究以核桃细菌性黑斑病菌CFBP2528、CFBP7179、CFBP8253、DW3F3、J303、NCPPB1447、Xaj417 7个菌株分泌蛋白质氨基酸序列为基础数据,利用蛋白质数据库、PHD、Protscale、TargetP 1.1 Server、SMART等网站在线预测分析其理化性质、二级结构、疏水性、转运肽及保守结构域等性质,明确核桃细菌性黑斑病菌的分泌蛋白质所具有的特征。结果表明,在所分析的7个菌株520个分泌蛋白质中,分泌蛋白质的理论等电点集中在6.01～7.00,蛋白质数量所占比例为26.92%;不稳定性系数集中在20.01～40.00,其蛋白质数量所占比例为63.65%;亲水值小于0的蛋白质数量所占比例为76.51%,亲水性最强的氨基酸残基中数量最多的是D,所占比例为13.64%,疏水性最强的氨基酸残基中数量最多的是L,所占比例为29.58%;分泌蛋白质均含有无规则卷曲、α螺旋、β折叠、TM(跨膜螺旋)二级结构,其所占比例分别为27.56%、27.17%、26.45%、1.03%;转运肽集中在分泌通路,其所占比例为95.38%;每个菌株平均有16个分泌蛋白质具有保守结构域,所占比例为21.35%。上述研究结果为深入解析核桃细菌性黑斑病菌分泌蛋白质的功能冗余性和多样性奠定了基础。

The bacterial black spot disease seriously affects the yield and quality of walnut, and it is one of the more serious diseases in the production process of walnut. Secreted proteins from plant pathogenic fungi, bacteria and oomycetes play important roles in their pathogenesis. In this study, based on the secreted protein sequences of seven strains of black spot bacteria such as CFBP2528, CFBP7179, CFBP8253, DW3F3, J303, NCPPB1447 and Xaj417, the protein databases, PHD, Protscale, TargetP 1.1 Server, SMART were used to predict the physicochemical properties, secondary structure, hydrophobicity, transit peptides and conserved domains, and clarify the characteristics of secreted proteins in the bacterial black spot pathogen of walnut. The results showed that the theoretical isoelectric point of 520 secreted proteins from seven strains was concentrated at 6.01- 7.00, and the protein accounted for 26.92%. The instability coefficient was concentrated at 20.01- 40.00, and the protein accounted for 63.65%. The proportion of proteins with hydrophilic value less than 0 was 76.51%. The most hydrophilic amino acid residue was D, accounting for 13.64%, the most hydrophobic amino acid residue was L, accounting for 29.58%. The secreted proteins all contained secondary structures such as random coil, alpha helix, beta strand, TM (transmembrane helix), accounting for 27.56%, 27.17%, 26.45% and 1.03%, respectively. The transit peptides were concentrated in the secretory pathway, accounting for 95.38%. On average, 16 secreted proteins of each strain had conserved domains, accounting for 21.35%. The above results lay a foundation for further analysis of the functional redundancy and diversity of secreted proteins in the bacterial black spot pathogen of walnut.