Prenylation plays an important role in diversifying the structure and function of secondary metabolites. Although several cyanobactin prenyltransferases have been characterized, their chemistries are mainly limited to the modification of electron-rich heteroatoms. Here we report a prenyltransferase, LimF, from Limnothrix sp. CACIAM 69d, geranylating the electron-deficient C2 atom of His imidazole. Interestingly, in addition to its native substrate, LimF also modifies diverse exotic peptides, including thioether-closed macrocycles. We have also serendipitously uncovered Tyr-O-geranylating activity as the secondary function of LimF, providing evolutional insight into the divergent repertoire of prenylated peptides produced by cyanobactin PTases. Crystallographic analysis of LimF complexed with a pentapeptide substrate and a prenyl donor analogue provides the structural basis for its His recognition and its bifunctionality. We also show the prenylation ability of LimF on various bioactive molecules containing an imidazole group, including non-amino acid small molecules, highlighting its potential as a versatile biocatalyst for chemically challenging imidazole C-geranylation.

异戊二烯化在使次级代谢物的结构和功能多样化方面发挥着重要作用。尽管已经对几种氰基细菌异戊二烯基转移酶进行了表征，但它们的化学作用主要限于修饰富电子杂原子。在这里，我们报告了来自Limnothrix sp的异戊二烯基转移酶 LimF 。CACIAM 69d，使His 咪唑的缺电子C 2 原子香叶化。有趣的是，除了其天然底物外，LimF 还修饰了多种外来肽，包括硫醚封闭的大环化合物。我们还偶然发现了 Tyr- O-作为 LimF 的次要功能的香叶酰化活性，提供了对由 cyanobactin PTases 产生的异戊二烯化肽的不同谱系的进化洞察。与五肽底物和异戊二烯供体类似物复合的 LimF 的晶体学分析为其 His 识别及其双功能提供了结构基础。我们还展示了 LimF 对各种含有咪唑基团的生物活性分子（包括非氨基酸小分子）的异戊二烯化能力，突出了其作为具有化学挑战性的咪唑C-香叶酰化的多功能生物催化剂的潜力。