PDF(Pubmed)
Abstract：
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 NH2, NHCH3 and N(CH3)2 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.
摘要：
N-甲基转移酶（NMT）催化的非核糖体肽（NRP）末端甲基化很少报道。这里,我们发现了一个NRP家族的迭代末端N-甲基化的真菌NMTLcsG，亮氨酸他汀类药物。基因缺失结果表明，LcsG是亮氨酸他汀类药物甲基化所必需的。体外测定和HRESI-MS-MS分析的结果揭示了各种亮氨酸他汀类药物C末端的NH2，NHCH3和N（CH3）2甲基化位点。LcsG催化产生新的脂肽，其中一些具有针对人类病原体新生隐球菌和植物病原体疫霉的有效抗生素特性。LcsG的多序列比对和定点诱变表明存在高度保守的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，靶向的N可以在这两个残基之间对接。因此，这项研究提出了一种增加NPR天然生物活性多样性的方法，以及NRPN甲基化的可能催化机理。
