Merrild Aske, Svenningsen Tiziana, Chevrette Marc G, Tørring Thomas
Department of Biological & Chemical Engineering, Aarhus University, Gustav Wieds vej 10D, 8000, Aarhus, Denmark.
Department of Microbiology & Cell Sciences, University of Florida, Gainesville, Florida, USA.
Angew Chem Int Ed Engl. 2025 May 12;64(20):e202425134. doi: 10.1002/anie.202425134. Epub 2025 Mar 5.
Triculamin is a ribosomally synthesized and post-translationally modified peptide (RiPP) lasso peptide with potent antimycobacterial activity, produced by an unusual, non-canonical biosynthetic gene cluster (BGC). In this study, we elucidate the biosynthetic pathway of triculamin through heterologous expression and show that the biosynthesis proceeds in the presence of a precursor (triA), macrocyclase (triC), and N-acetyltransferase (triT). Through in vitro triT acetylation and bioactivity assays, we show that acetylation functions as a resistance mechanism. Genomic searches of triculamin BGC genes across bacteria show that triculamin is more widely distributed than previously anticipated, as triculamin-like core peptides are found in at least three phyla in contrast to previously described lasso peptides that are typically restricted to one phylum. Triculamin BGCs with both canonical and non-canonical RiPP biosynthetic genes were identified. Two strains containing canonical triculamin-like BGCs were chemically characterized and shown to produce the novel triculamin-like lasso peptides palmamin and gelatinamin, the latter of which appears to have an unprecedented additional ring formation. Detailed phylogenetic investigation of the macrocyclases from triculamin-like BGCs suggests that these molecules are products of convergent evolution. These findings broaden the evolutionary and functional landscape of lasso peptides, revealing their unexpected diversification and cross-phylum distribution.
曲库拉明是一种核糖体合成并经翻译后修饰的肽（RiPP）套索肽，具有强大的抗分枝杆菌活性，由一个不寻常的、非经典的生物合成基因簇（BGC）产生。在本研究中，我们通过异源表达阐明了曲库拉明的生物合成途径，并表明生物合成过程在前体（triA）、大环化酶（triC）和N - 乙酰转移酶（triT）存在的情况下进行。通过体外triT乙酰化和生物活性测定，我们表明乙酰化起到了抗性机制的作用。对细菌中曲库拉明BGC基因的基因组搜索表明，曲库拉明的分布比以前预期的更广泛，因为与先前描述的通常局限于一个门的套索肽相比，在至少三个门中发现了类似曲库拉明的核心肽。鉴定出了具有经典和非经典RiPP生物合成基因的曲库拉明BGC。对含有经典曲库拉明样BGC的两株菌株进行了化学表征，结果表明它们产生了新型的类似曲库拉明的套索肽棕榈明和明胶明，其中后者似乎有一个前所未有的额外环形成。对来自类似曲库拉明BGC的大环化酶的详细系统发育研究表明，这些分子是趋同进化的产物。这些发现拓宽了套索肽的进化和功能格局，揭示了它们意想不到的多样化和跨门分布。
