Biosynthesis of 3"-demethyl-gentamicin C components by genN disruption strain of Micromonospora echinospora and test their antimicrobial activities in vitro
Biosynthesis of 3"-demethyl-gentamicin C components by genN disruption strain of Micromonospora echinospora and test their antimicrobial activities in vitro
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DOI：
10.1016/j.micres.2016.01.005
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发表时间：
2016-01-01
影响因子：
6.7
通讯作者：
Xia, Huanzhang
中科院分区：
文献类型：
--
作者：
Ni, Xianpu;Zong, Tingting;Xia, Huanzhang
庆大霉素主要由四种组分组成，它们在C-6'位具有不同的甲基化模式。甲基对庆大霉素的抗菌活性有显著影响。序列分析预测GenN是庆大霉素生物合成途径中的甲基转移酶。为了研究genN基因的功能，对棘孢小单孢菌（Micromonospora echinospora）的genN基因进行了破坏。genN破坏菌株产生3“-N-去甲基-庆大霉素C复合物而不是庆大霉素C复合物。本研究从破坏菌发酵液中分离纯化了3“-N-去甲基庆大霉素C1 a，并利用质谱和核磁共振对其结构进行了鉴定。除庆大霉素C1 a、C2和C2 a的3“-N-脱甲基产物外，还检测到庆大霉素C1的2种3”-N-脱甲基产物，推断为C-6“差向异构体，源于6”-N甲基转移酶底物特异性降低。为了探讨3“-N-甲基对庆大霉素抗菌活性的影响，对这些去甲基庆大霉素类似物进行了体外抗菌活性测试。3“-N-去甲基庆大霉素组分与庆大霉素的相应组分具有相同的活性。生物活性测定结果表明，3“-N-甲基对庆大霉素的活性影响不大。然而，这些高度生物活性的化合物为创造新的高效氨基糖苷类抗生素提供了独特的机会。(C)2016 Elsevier GmbH. All rights reserved.
Gentamicin consists primarily of four components, which have different patterns of methylation at C-6' position. The methyl groups have a significant impact on gentamicin antimicrobial activity. Sequence analysis predicted that GenN was a methyltransferase in the gentamicin biosynthetic pathway. To study the function of genN, it was disrupted in Micromonospora echinospora. The genN disruption strains produced 3 ''-N-demethyl-gentamicin C complex instead of the gentamicin C complex. In this study, 3 ''-N-demethyl gentamicin C1a was purified from the broth of disruption strain, and its structure was elucidated using MS and NMR. Besides 3 ''-N-demethyl products corresponding to gentamicin C1a, C2, and C2a, two 3 ''-N-demethyl products corresponding to gentamicin C1 were detected, which were concluded as C-6' epimers originating from decreased substrate specificity of 6'-N methyltransferase. To explore the effects of 3 ''-N-methyl on gentamicin antimicrobial activity, antimicrobial activity of these demethyl gentamicin analogues were tested in vitro. 3 ''-N-Demethyl gentamicin components have identical activity with corresponding components of gentamicin. The results of bioassays showed that the 3 ''-N-methyl group has little impact on gentamicin activity. However, these highly bioactive compounds afforded a unique opportunity for creating new and high potent aminoglycoside antibiotics. (C) 2016 Elsevier GmbH. All rights reserved.