Insights into methyltransferase specificity and bioactivity of derivatives of the antibiotic plantazolicin.
Insights into methyltransferase specificity and bioactivity of derivatives of the antibiotic plantazolicin.
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DOI：
10.1021/cb501042a
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发表时间：
2015-05-15
影响因子：
4
通讯作者：
Nair SK
中科院分区：
文献类型：
--
作者：
Hao Y;Saint-Vincent PMB;Sharma A;Mitchell DA;Nair SK
肽类抗生素是一类构象受限的天然产物，具有越来越大的药用价值。Plantazolicin（PZN）是一种线性多杂环天然产物，对炭疽杆菌具有高度选择性和有效活性。PZN的生物活性取决于其N-末端Arg残基通过S-腺苷甲硫氨酸依赖性甲基转移酶的二甲基化。在这里，我们探讨了两个同源PZN甲基转移酶的底物耐受性进行动力学分析的酶对合成面板的截短PZN类似物含有N-末端精氨酸残基。X射线共晶结构的PZN甲基转移酶与这些含杂环的基板提供了一个基本原理，了解这些酶的严格的基板特异性。动力学研究的结构指导，位点特异性的变体允许分配的残基管理催化和底物范围。微生物测试进一步揭示，在N-末端Arg二甲基化后，五杂环化PZN类似物保留了有效的抗B。炭疽活性，几乎等于全长PZN。这些研究可能是有用的，在生物合成工程的天然产物类似物具有不同的生物活性的档案，证明了我们的鉴定截短plantazolicin衍生物，对耐甲氧西林金黄色葡萄球菌（MRSA）的活性。
Peptide antibiotics represent a class of conformationally-constrained natural products of growing pharmaceutical interest. Plantazolicin (PZN) is a linear, polyheterocyclic natural product with highly selective and potent activity against the anthrax-causing bacterium, Bacillus anthracis. The bioactivity of PZN is contingent on dimethylation of its N-terminal Arg residue by an S-adenosylmethionine-dependent methyltransferase. Here, we explore the substrate tolerances of two homologous PZN methyltransferases by carrying out kinetic analyses of the enzymes against a synthetic panel of truncated PZN analogs containing the N-terminal Arg residue. X-ray cocrystal structures of the PZN methyltransferases with each of these heterocycle-containing substrates provide a rationale for understanding the strict substrate specificity of these enzymes. Kinetic studies of structure-guided, site-specific variants allowed for the assignment of residues governing catalysis and substrate scope. Microbiological testing further revealed that upon dimethylation of the N-terminal Arg, a pentaheterocyclized PZN analog retained potent anti-B. anthracis activity, nearly equal to that of full-length PZN. These studies may be useful in the biosynthetic engineering of natural product analogs with different bioactivity profiles, as demonstrated by our identification of a truncated plantazolicin derivative that is active against methicillin-resistant Staphylococcus aureus (MRSA).