Kim Sun-Young, Parker Jennifer K, Gonzalez-Magaldi Monica, Telford Mady S, Leahy Daniel J, Davies Bryan W
bioRxiv. 2023 Jan 26:2023.01.26.525739. doi: 10.1101/2023.01.26.525739.
Microcins are peptide antibiotics secreted by Gram-negative bacteria that inhibit the growth of neighboring microbes. They are exported from the cytosol to the environment in a one-step process through a specific type I secretion system (T1SS). While the rules governing export of natural or non-native substrates have been resolved for T1SSs that secrete large proteins, relatively little is known about substrate requirements for peptides exported through T1SSs that secrete microcins. Here, we investigate the prototypic microcin V T1SS from and show it can export a remarkably wide range of natural and synthetic peptides. We demonstrate that secretion through this system is not affected by peptide charge or hydrophobicity and appears only constrained by peptide length. A varied range of bioactive peptides, including an antibacterial peptide, a microbial signaling factor, a protease inhibitor, and a human hormone, can all be secreted and elicit their intended biological effect. Secretion through this system is not limited to , and we demonstrate its function in additional Gram-negative species that can inhabit the gastrointestinal tract. Our findings uncover the highly promiscuous nature of peptide export thorough the microcin V T1SS, which has implications for native cargo capacity and use of Gram-negative bacteria for peptide research and delivery.
Microcin type I secretion systems in Gram-negative bacteria transport antibacterial peptides from the cytoplasm to the extracellular environment in single step. In nature, each microcin secretion system is generally paired with a specific peptide. We know little about the export capacity of these transporters and how peptide sequence influences secretion. Here, we investigate the microcin V type I secretion system. Remarkably, our studies show this system can export diverse peptides and is only limited by peptide length. Furthermore, we demonstrate that various bioactive peptides can be secreted, and this system can be used in Gram-negative species that colonize the gastrointestinal tract. These finding expand our understanding of secretion through type I systems and their potential uses in peptide applications.
微菌素是革兰氏阴性菌分泌的肽类抗生素，可抑制邻近微生物的生长。它们通过特定的I型分泌系统（T1SS）以一步过程从细胞质输出到细胞外环境。虽然对于分泌大蛋白的T1SS，控制天然或非天然底物输出的规则已经明确，但对于通过分泌微菌素的T1SS输出的肽的底物要求了解相对较少。在这里，我们研究了来自[具体来源未给出]的原型微菌素V T1SS，并表明它可以输出范围广泛的天然和合成肽。我们证明，通过该系统的分泌不受肽电荷或疏水性的影响，似乎仅受肽长度的限制。各种生物活性肽，包括抗菌肽、微生物信号因子、蛋白酶抑制剂和人类激素，都可以被分泌并发挥其预期的生物学作用。通过该系统的分泌不限于[具体范围未给出]，我们证明了它在其他可栖息于胃肠道的革兰氏阴性菌中的功能。我们的发现揭示了通过微菌素V T1SS进行肽输出的高度混杂性质，这对天然货物运输能力以及革兰氏阴性菌在肽研究和递送中的应用具有重要意义。
革兰氏阴性菌中的微菌素I型分泌系统将抗菌肽从细胞质一步运输到细胞外环境。在自然界中，每个微菌素分泌系统通常与一种特定的肽配对。我们对这些转运蛋白的输出能力以及肽序列如何影响分泌了解甚少。在这里，我们研究了微菌素V型I分泌系统。值得注意的是，我们的研究表明该系统可以输出多种肽，并且仅受肽长度的限制。此外，我们证明了各种生物活性肽可以被分泌，并且该系统可用于在胃肠道定殖的革兰氏阴性菌。这些发现扩展了我们对通过I型系统分泌及其在肽应用中的潜在用途的理解。
