Department of Microbiology, Molecular Genetics, and Immunology, University of Kansas Medical Center, Kansas City, Kansas, USA.
Microbiol Spectr. 2023 Feb 14;11(1):e0303022. doi: 10.1128/spectrum.03030-22. Epub 2023 Jan 16.
Owing to extensive metagenomic studies, we now have access to numerous sequences of novel bacteriocin-like antimicrobial peptides encoded by various cultivable and noncultivable bacteria. However, relatively rarely, we even have access to these cultivable strains to examine the potency and the targets of the predicted bacteriocins. In this study, we evaluated a heterologous biosynthetic system to produce biologically active nonnative novel lantibiotics, which are modified bacteriocins. We chose Streptococcus mutans, a dental pathogen, as the host organism because it is genetically easy to manipulate and is inherently a prolific producer of various bacteriocins. We chose the S. mutans T8 strain as the host, which produces the lantibiotic mutacin II, to express 10 selected homologs of mutacin II identified from GenBank. These lantibiotic peptides either are novel or have been studied very minimally. The core regions of the selected lantibiotic peptides were fused to the leader sequence of the mutacin II peptide and integrated into the chromosome such that the core region of the native mutacin II was replaced with the new core sequences. By this approach, using the mutacin II biosynthesis machinery, we obtained one bioactive novel lantibiotic peptide with 52% different residues compared to the mutacin II core region. This unknown lantibiotic is encoded by Streptococcus agalactiae and Streptococcus ovuberis strains. Since this peptide displays some homology with nukacin ISK-1, we named it nukacin Spp. 2. This study demonstrated that the mutacin II biosynthesis machinery can be successfully used as an efficient system for the production of biologically active novel lantibiotics. In this study, we report for the first time that Streptococcus mutans can be used as a host to produce various nonnative lantibiotics. We showed that in the T8 strain, we could produce bioactive lacticin 481 and nukacin ISK-1, both of which are homologs of mutacin II, using T8's modification and secretion apparatus. Similarly, we also synthesized a novel bioactive lantibiotic, which we named nukacin Spp. 2.
由于广泛的宏基因组学研究，我们现在可以获得许多由各种可培养和不可培养细菌编码的新型细菌素样抗菌肽的序列。然而，相对较少的情况下，我们甚至可以获得这些可培养的菌株来检查预测的细菌素的效力和靶标。在这项研究中，我们评估了一种异源生物合成系统来生产具有生物活性的非天然新型类细菌素，即经过修饰的细菌素。我们选择变形链球菌，一种口腔病原体，作为宿主生物体，因为它在遗传上很容易操作，并且本质上是各种细菌素的丰富生产者。我们选择了 S. mutans T8 菌株作为宿主，该菌株产生万古霉素 II，以表达从 GenBank 中鉴定的 10 种万古霉素 II 的同源物。这些细菌素肽要么是新型的，要么研究得非常少。所选细菌素肽的核心区域与万古霉素 II 肽的前导序列融合，并整合到染色体中，使得天然万古霉素 II 的核心区域被新的核心序列取代。通过这种方法，使用万古霉素 II 生物合成机制，我们获得了一种具有 52%不同残基的生物活性新型细菌素肽，与万古霉素 II 核心区域相比。这种未知的细菌素由酿脓链球菌和无乳链球菌菌株编码。由于该肽与 nukacin ISK-1 具有一定的同源性，我们将其命名为 nukacin Spp. 2。这项研究表明，万古霉素 II 生物合成机制可以成功地用作生产具有生物活性的新型细菌素的有效系统。在这项研究中，我们首次报道变形链球菌可作为宿主生产各种非天然细菌素。我们表明，在 T8 菌株中，我们可以使用 T8 的修饰和分泌装置生产具有生物活性的乳酸杆菌 481 和 nukacin ISK-1，它们都是万古霉素 II 的同源物。同样，我们还合成了一种新型的生物活性细菌素，我们将其命名为 nukacin Spp. 2。
