School of Microbiology, University College Cork, Cork, Ireland.
APC Microbiome Ireland, University College Cork, Cork, Ireland.
Appl Environ Microbiol. 2020 Jul 20;86(15). doi: 10.1128/AEM.00984-20.
Nisin A is a potent antimicrobial with potential as an alternative to traditional antibiotics, and a number of genetically modified variants have been created that target clinically relevant pathogens. In addition to antimicrobial activity, nisin autoregulates its own production via a signal transduction pathway, a property that has been exploited in a protein expression system termed the nisin-controlled gene expression (NICE) system. Although NICE has become one of the most popular protein expression systems, one drawback is that the inducer peptide, nisin A, also has inhibitory activity. It has already been demonstrated that the N-terminal region of nisin A contributes to antimicrobial activity and signal transduction properties; therefore, we conducted bioengineering of nisin at positions Pro9 and Gly10 within ring B to produce a bank of variants that could potentially be used as alternative induction peptides. One variant, designated nisin M, has threonines at positions 9 and 10 and retains induction capacity comparable to that of wild-type nisin A, while most of the antimicrobial activity is abolished. Further analysis confirmed that nisin M produces a mix of peptides as a result of different degrees of dehydration of the two threonines. We show that nisin M exhibits potential as a more suitable alternative to nisin A for the expression of proteins that may be difficult to express or for production of proteins in strains that are sensitive to wild-type nisin. Moreover, it may address the increasing demand by industry for optimization of peptide fermentations to increase yields or production rates. This study describes the generation of a nisin variant with superior characteristics for use in the NICE protein expression system. The variant, termed nisin M, retains an induction capacity comparable to that of wild-type nisin A but exhibits significantly reduced antimicrobial activity and can therefore be used at concentrations that are normally toxic to the expression host.
乳链菌肽 A 是一种有效的抗菌剂,具有替代传统抗生素的潜力,并且已经创建了许多针对临床相关病原体的基因改造变体。除了抗菌活性外,乳链菌肽还通过信号转导途径自我调节其自身的产生,这种特性已在一种称为乳链菌肽控制基因表达 (NICE) 系统的蛋白质表达系统中得到利用。尽管 NICE 已成为最受欢迎的蛋白质表达系统之一,但一个缺点是诱导肽乳链菌肽 A 也具有抑制活性。已经证明,乳链菌肽 A 的 N 端区域有助于抗菌活性和信号转导特性;因此,我们在环 B 内的 Pro9 和 Gly10 位置对乳链菌肽进行了生物工程改造,产生了一系列可能用作替代诱导肽的变体。一种变体,命名为乳链菌肽 M,在位置 9 和 10 具有苏氨酸,保留了与野生型乳链菌肽 A 相当的诱导能力,而大部分抗菌活性被消除。进一步的分析证实,乳链菌肽 M 由于两个苏氨酸的不同程度脱水而产生混合肽。我们表明,乳链菌肽 M 具有作为替代乳链菌肽 A 的潜力,可用于表达可能难以表达的蛋白质,或用于对野生型乳链菌肽敏感的菌株生产蛋白质。此外,它可能满足行业对优化肽发酵以提高产量或生产速度的日益增长的需求。本研究描述了一种具有更优特性的乳链菌肽变体的产生,可用于 NICE 蛋白质表达系统。该变体,命名为乳链菌肽 M,保留了与野生型乳链菌肽 A 相当的诱导能力,但表现出显著降低的抗菌活性,因此可以在通常对表达宿主有毒的浓度下使用。