State Key Laboratory of Vegetable Biobreeding, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, 100081, Beijing, China.
Microbial Processes and Interactions (MiPI), TERRA Teaching and Research Centre, Gembloux Agro-Bio Tech, University of Liège, 5030, Gembloux, Belgium.
Commun Biol. 2024 Jun 22;7(1):757. doi: 10.1038/s42003-024-06467-0.
N-methyltransferase (NMT)-catalyzed methylation at the termini of nonribosomal peptides (NRPs) has rarely been reported. Here, we discover a fungal NMT LcsG for the iterative terminal N-methylation of a family of NRPs, leucinostatins. Gene deletion results suggest that LcsG is essential for leucinostatins methylation. Results from in vitro assays and HRESI-MS-MS analysis reveal the methylation sites as NH, NHCH and N(CH) in the C-terminus of various leucinostatins. LcsG catalysis yields new lipopeptides, some of which demonstrate effective antibiotic properties against the human pathogen Cryptococcus neoformans and the plant pathogen Phytophthora infestans. Multiple sequence alignments and site-directed mutagenesis of LcsG indicate the presence of a highly conserved SAM-binding pocket, along with two possible active site residues (D368 and D395). Molecular dynamics simulations show that the targeted N can dock between these two residues. Thus, this study suggests a method for increasing the variety of natural bioactivity of NPRs and a possible catalytic mechanism underlying the N-methylation of NRPs.
N-甲基转移酶（NMT）催化非核糖体肽（NRP）末端的甲基化很少有报道。在这里，我们发现了一种真菌 NMT LcsG，它可以对一组 NRP，亮抑酶肽进行迭代末端 N-甲基化。基因缺失结果表明 LcsG 是亮抑酶肽甲基化所必需的。体外测定和 HRESI-MS-MS 分析结果表明，各种亮抑酶肽的 C 末端甲基化位点为 NH、NHCH 和 N(CH)。LcsG 催化生成新的脂肽，其中一些对人类病原体新型隐球菌和植物病原体致病疫霉具有有效的抗菌特性。LcsG 的多序列比对和定点突变表明存在一个高度保守的 SAM 结合口袋，以及两个可能的活性位点残基（D368 和 D395）。分子动力学模拟表明，靶标 N 可以在这两个残基之间对接。因此，本研究提出了一种增加 NPR 天然生物活性多样性的方法，以及 NRP N-甲基化的可能催化机制。
