Directionality and Coordination of Dehydration and Ring Formation during Biosynthesis of the Lantibiotic Nisin
Directionality and Coordination of Dehydration and Ring Formation during Biosynthesis of the Lantibiotic Nisin
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DOI：
10.1074/jbc.m109.026690
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发表时间：
2009-09-18
影响因子：
4.8
通讯作者：
Kuipers, Oscar P.
中科院分区：
文献类型：
--
作者：
Lubelski, Jacek;Khusainov, Rustem;Kuipers, Oscar P.
羊毛硫抗生素乳链菌素是一种有效的抗菌物质，含有不寻常的羊毛硫氨酸环和脱水氨基酸残基，由乳酸乳球菌产生。最近，乳链菌肽生物合成机制已被应用于在除乳链菌肽之外的肽中引入羊毛硫氨酸环，具有潜在的治疗用途。由于分离所提出的合成酶复合物（NisBTC）存在困难，有关乳链菌肽酶促生物合成的机制信息很少。在这里，我们介绍了一些影响环形成的乳链菌肽突变体的分子特征。我们系统地研究了这些突变如何影响脱水事件，脱水事件是由脱水酶 NisB 酶促完成的。阻碍环形成的特定突变使得直接跟随环且通常未经修饰的丝氨酸残基脱水。综合信息得出的结论是：1) 乳链菌肽生物合成是一种有组织的定向过程，从分子的 N 末端开始，继续向 C 末端延伸；2) NisB 和 NisC 是交替酶，其活性以重复的方式依次进行。因此，脱水和环化过程在时间和空间上不是分开的。根据这些结果和先前的知识，提出了乳链菌肽成熟过程中事件序列的工作模型。
The lantibiotic nisin is a potent antimicrobial substance, which contains unusual lanthionine rings and dehydrated amino acid residues and is produced by Lactococcus lactis. Recently, the nisin biosynthetic machinery has been applied to introduce lanthionine rings in peptides other than nisin with potential therapeutic use. Due to difficulties in the isolation of the proposed synthetase complex (NisBTC), mechanistic information concerning the enzymatic biosynthesis of nisin is scarce. Here, we present the molecular characterization of a number of nisin mutants that affect ring formation. We have investigated in a systematic manner how these mutations influence dehydration events, which are performed enzymatically by the dehydratase NisB. Specific mutations that hampered ring formation allowed for the dehydration of serine residues that directly follow the rings and are normally unmodified. The combined information leads to the conclusion that 1) nisin biosynthesis is an organized directional process that starts at the N terminus of the molecule and continues toward the C terminus, and 2) NisB and NisC are alternating enzymes, whose activities follow one after another in a repetitive way. Thus, the dehydration and cyclization processes are not separated in time and space. On the basis of these results and previous knowledge, a working model for the sequence of events in the maturation of nisin is proposed.