中文摘要：

【目的】阐明羊毛硫细菌素bovicin HJ50前导肽的二级结构对原肽修饰和加工的影响规律。【方法】采用半体外生物合成系统构建bovicin HJ50前导肽突变体,然后利用MALDI-TOF质谱鉴定成熟肽的修饰情况。同时,结合HPLC和抑菌活性分析其对成熟肽加工效率的影响。【结果】我们构建了6个bovicin HJ50前导肽二级结构相关的突变体（F-16A,V-15E,E-14L,E-8P,L-7D,L-4K）。F-16A,V-15E,L-4K几乎不影响修饰和加工;E-14L和E-8P的修饰则发生了变化;另发现L-7D导致加工过程受到强烈抑制。【结论】Bovicin HJ50前导序列中保守的螺旋结构区对修饰酶BovM和蛋白酶BovT150活性都有不同程度影响,其二级结构的维持对bovicin HJ50的修饰和加工具有重要作用。

英文摘要：

[Objective] Elucidating the correlation between the secondary structure of the leader peptide of lantibiotic bovicin HJ50 and its modification and processing.[Methods] The variants with mutated leader peptide were synthesized by semi-in vitro biosynthesis,and their modification pattern were then analyzed by MALDI-TOF MS.At the same time,the effect of leader peptide mutants on processing the modified propeptide was examined by HPLC and antimicrobial activity.[Results] We constructed 6 mutants（F-16A,V-15E,E-14L,E-8P,L-7D,L-4K） involved in forming secondary structure of the bovicin HJ50 leader peptide.F-16A,V-15E,L-4K showed very little effect on modification and processing whereas E-14L and E-8P caused changes in modification.In addition,we found that L-7D strongly affected the processing.[Conclusion] The conserved helix structure in the leader peptide of bovicin HJ50 was closely related to the activity of BovM and BovT150,and the presence of secondary structure was very important to modification and processing of bovicin HJ50.