聚醚類離子載體是一類獨特的具有廣譜生物活性的聚酮化合物，在抗耐藥菌,、抗寄生蟲,、抗腫瘤方面極具開發(fā)潛力。目前已知的聚醚類離子載體無一例外均由放線菌產(chǎn)生,，因此放線菌是這類活性物質(zhì)的重要來源和生物合成研究的理想材料,。
中科院微生物研究所微生物資源前期開發(fā)國家重點實驗室黃英研究組通過對已知的聚醚類離子載體生物合成基因簇進行比較，發(fā)現(xiàn)其中均包含一個關(guān)鍵的后修飾酶基因——環(huán)氧化酶基因(epo),，該基因負責(zé)合成途徑中不飽和聚醚中間體的環(huán)氧化反應(yīng),。研究團隊設(shè)計了該基因的特異引物，對逾千株來自不同生境和不同科屬的放線菌進行了PCR篩選,，結(jié)果表明,，僅4個屬的放線菌具有產(chǎn)生聚醚抗生素的潛力,，而來自酸性土壤的嗜酸鏈霉菌最具潛力，所設(shè)計的引物也適合檢測諸多基因簇未知的聚醚類離子載體產(chǎn)生菌的環(huán)氧化酶基因,。隨后對13株陽性菌株進行了產(chǎn)物分析,，證實它們均產(chǎn)生聚醚類抗生素，且環(huán)氧化酶基因序列與聚醚產(chǎn)物結(jié)構(gòu)之間具有明顯的相關(guān)性,，并獲得了兩個新結(jié)構(gòu)類似物,。由此建立了從放線菌中快速鑒別已知聚醚并發(fā)現(xiàn)未知聚醚的基因篩選策略。
該項研究提供了一個基于次級代謝生物合成后修飾酶基因篩選發(fā)現(xiàn)新天然產(chǎn)物的典型范例,，對微生物資源的發(fā)掘利用具有指導(dǎo)意義,。（生物谷Bioon.com）
生物谷推薦原文出處：
Applied and Environmental Microbiology DOI：10.1128/AEM.02915-10
Genetic Screening Strategy for Rapid Access to Polyether Ionophore Producers and Products in Actinomycetes
Hao Wang, Ning Liu, Lijun Xi, Xiaoying Rong, Jisheng Ruan, and Ying Huang
Polyether ionophores are a unique class of polyketides with broad-spectrum activity and outstanding potency for the control of drug-resistant bacteria and parasites, and they are produced exclusively by actinomycetes. A special epoxidase gene encoding a critical tailoring enzyme involved in the biosynthesis of these compounds has been found in all five of the complete gene clusters of polyether ionophores published so far. To detect potential producer strains of these antibiotics, a pair of degenerate primers was designed according to the conserved regions of the five known polyether epoxidases. A total of 44 putative polyether epoxidase gene-positive strains were obtained by the PCR-based screening of 1,068 actinomycetes isolated from eight different habitats and 236 reference strains encompassing eight major families of Actinomycetales. The isolates spanned a wide taxonomic diversity based on 16S rRNA gene analysis, and actinomycetes isolated from acidic soils seemed to be a promising source of polyether ionophores. Four genera were detected to contain putative polyether epoxidases, including Micromonospora, which has not previously been reported to produce polyether ionophores. The designed primers also detected putative epoxidase genes from diverse known producer strains that produce polyether ionophores unrelated to the five published gene clusters. Moreover, phylogenetic and chemical analyses showed a strong correlation between the sequence of polyether epoxidases and the structure of encoded polyethers. Thirteen positive isolates were proven to be polyether ionophore producers as expected, and two new analogues were found. These results demonstrate the feasibility of using this epoxidase gene screening strategy to aid the rapid identification of known products and the discovery of unknown polyethers in actinomycetes.
