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Designed biosynthesis of 25-methyl and 25-ethyl ivermectin with enhanced insecticidal activity by domain swap of avermectin polyketide synthase.

Zhang J, Yan YJ, An J, Huang SX, Wang XJ, Xiang WS - Microb. Cell Fact. (2015)

Bottom Line: Moreover, the insecticidal activity of the mixture of 25-methyl and 25-ethyl ivermectin was 2.5-fold and 5.7-fold higher than that of milbemycin A3/A4 against C. elegans and the second-instar larva of Mythimna separate, respectively.Two new avermectin derivatives 25-methyl and 25-ethyl ivermectin were generated by the domain swap of avermectin PKS.The enhanced insecticidal activity of 25-methyl and 25-ethyl ivermectin implied the potential use as insecticide in agriculture.

View Article: PubMed Central - PubMed

Affiliation: School of Life Science, Northeast Agricultural University, No. 59 Mucai Street, Xiangfang District, Harbin, 150030, China. zhangji@neau.edu.cn.

ABSTRACT

Background: Avermectin and milbemycin are important 16-membered macrolides that have been widely used as pesticides in agriculture. However, the wide use of these pesticides inevitably causes serious drug resistance, it is therefore imperative to develop new avermectin and milbemycin analogs. The biosynthetic gene clusters of avermectin and milbemycin have been identified and the biosynthetic pathways have been elucidated. Combinatorial biosynthesis by domain swap provides an efficient strategy to generate chemical diversity according to the module polyketide synthase (PKS) assembly line.

Results: The substitution of aveDH2-KR2 located in avermectin biosynthetic gene cluster in the industrial avermectin-producing strain Streptomyces avermitilis NA-108 with the DNA regions milDH2-ER2-KR2 located in milbemycin biosynthetic gene cluster in Streptomyces bingchenggensis led to S. avermitilis AVE-T27, which produced ivermectin B1a with high yield of 3450 ± 65 μg/ml. The subsequent replacement of aveLAT-ACP encoding the loading module of avermectin PKS with milLAT-ACP encoding the loading module of milbemycin PKS led to strain S. avermitilis AVE-H39, which produced two new avermectin derivatives 25-ethyl and 25-methyl ivermectin (1 and 2) with yields of 951 ± 46 and 2093 ± 61 μg/ml, respectively. Compared to commercial insecticide ivermectin, the mixture of 25-methyl and 25-ethyl ivermectin (2:1 = 3:7) exhibited 4.6-fold increase in insecticidal activity against Caenorhabditis elegans. Moreover, the insecticidal activity of the mixture of 25-methyl and 25-ethyl ivermectin was 2.5-fold and 5.7-fold higher than that of milbemycin A3/A4 against C. elegans and the second-instar larva of Mythimna separate, respectively.

Conclusions: Two new avermectin derivatives 25-methyl and 25-ethyl ivermectin were generated by the domain swap of avermectin PKS. The enhanced insecticidal activity of 25-methyl and 25-ethyl ivermectin implied the potential use as insecticide in agriculture. Furthermore, the high yield and genetic stability of the engineered strains S. avermitilis AVE-T27 and AVE-H39 suggested the enormous potential in industrial production of the commercial insecticide ivermectin and 25-methyl/25-ethyl ivermectins, respectively.

No MeSH data available.


Related in: MedlinePlus

The structures of avermectins, milbemycins, and 25-methyl/25-ethyl ivermectin (1 and 2)
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Fig1: The structures of avermectins, milbemycins, and 25-methyl/25-ethyl ivermectin (1 and 2)

Mentions: Avermectins and milbemycins (Fig. 1), the 16-membered macrolide antibiotics with potent anthelmintic and insecticidal activity, have been widely used for broad-spectrum parasite control in agricultural, medical, and veterinary fields [1–3]. They are structurally related compounds with structural differences at C25, C22–C23, and C13, leading to their own unique ‘spectral fingerprint’ with various strengths and dosage-limiting species. The subsequent chemically modification of avermectins and milbemycins resulted in series of analogs, some of which are commercially developed as anthelmintics and insecticides, such as ivermectin, selamectin, abamectin, emamectin, doramectin, milbemycin oxime, lepimectin, and latidectin [2]. Among these analogs, ivermectin (22,23-dihydroavermectin B1), showing the same effective antiparasitic activity and lesser toxic side effect than avermectins B1, has been worldwide used as an anthelmintic for livestock and companion animals and as an agricultural insecticide. Moreover, ivermectin has also been applied in human medicine, particularly treatment of onchocerciasis and lymphatic filariasis [4]. In the case of milbemycins, moxidectin is currently undergoing a phase III clinical trial to compare its efficacy with ivermectin in subjects with Onchocerca volvulus infection [1]; milbemycin oxime has been used against intestinal nematodes in dogs and cats, against adult heartworm in dogs, and against ectoparasites in companion animals [5]. Recently, it has been reported that ivermectin, selamectin and moxidectin demonstrated antibacterial activity against Mycobacterium tuberculosis, especially the multidrug-resistant and extensively drug-resistant clinical strains [1]. The approval for clinical and veterinary uses as well as the documented pharmacokinetic and safety profiles of these compounds make them potential therapeutic options for treating M. tuberculosis. The outstanding activities of avermectins and milbemycins together with the potential uses in the filed of human medicine and agriculture stimulate the semisynthetic derivatives of avermectins and milbemycins. On the other hand, the wide use of avermectins in agriculture has inevitably caused serious drug resistance [2], it is therefore imperative to develop novel avermectins.Fig. 1


Designed biosynthesis of 25-methyl and 25-ethyl ivermectin with enhanced insecticidal activity by domain swap of avermectin polyketide synthase.

Zhang J, Yan YJ, An J, Huang SX, Wang XJ, Xiang WS - Microb. Cell Fact. (2015)

The structures of avermectins, milbemycins, and 25-methyl/25-ethyl ivermectin (1 and 2)
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4581413&req=5

Fig1: The structures of avermectins, milbemycins, and 25-methyl/25-ethyl ivermectin (1 and 2)
Mentions: Avermectins and milbemycins (Fig. 1), the 16-membered macrolide antibiotics with potent anthelmintic and insecticidal activity, have been widely used for broad-spectrum parasite control in agricultural, medical, and veterinary fields [1–3]. They are structurally related compounds with structural differences at C25, C22–C23, and C13, leading to their own unique ‘spectral fingerprint’ with various strengths and dosage-limiting species. The subsequent chemically modification of avermectins and milbemycins resulted in series of analogs, some of which are commercially developed as anthelmintics and insecticides, such as ivermectin, selamectin, abamectin, emamectin, doramectin, milbemycin oxime, lepimectin, and latidectin [2]. Among these analogs, ivermectin (22,23-dihydroavermectin B1), showing the same effective antiparasitic activity and lesser toxic side effect than avermectins B1, has been worldwide used as an anthelmintic for livestock and companion animals and as an agricultural insecticide. Moreover, ivermectin has also been applied in human medicine, particularly treatment of onchocerciasis and lymphatic filariasis [4]. In the case of milbemycins, moxidectin is currently undergoing a phase III clinical trial to compare its efficacy with ivermectin in subjects with Onchocerca volvulus infection [1]; milbemycin oxime has been used against intestinal nematodes in dogs and cats, against adult heartworm in dogs, and against ectoparasites in companion animals [5]. Recently, it has been reported that ivermectin, selamectin and moxidectin demonstrated antibacterial activity against Mycobacterium tuberculosis, especially the multidrug-resistant and extensively drug-resistant clinical strains [1]. The approval for clinical and veterinary uses as well as the documented pharmacokinetic and safety profiles of these compounds make them potential therapeutic options for treating M. tuberculosis. The outstanding activities of avermectins and milbemycins together with the potential uses in the filed of human medicine and agriculture stimulate the semisynthetic derivatives of avermectins and milbemycins. On the other hand, the wide use of avermectins in agriculture has inevitably caused serious drug resistance [2], it is therefore imperative to develop novel avermectins.Fig. 1

Bottom Line: Moreover, the insecticidal activity of the mixture of 25-methyl and 25-ethyl ivermectin was 2.5-fold and 5.7-fold higher than that of milbemycin A3/A4 against C. elegans and the second-instar larva of Mythimna separate, respectively.Two new avermectin derivatives 25-methyl and 25-ethyl ivermectin were generated by the domain swap of avermectin PKS.The enhanced insecticidal activity of 25-methyl and 25-ethyl ivermectin implied the potential use as insecticide in agriculture.

View Article: PubMed Central - PubMed

Affiliation: School of Life Science, Northeast Agricultural University, No. 59 Mucai Street, Xiangfang District, Harbin, 150030, China. zhangji@neau.edu.cn.

ABSTRACT

Background: Avermectin and milbemycin are important 16-membered macrolides that have been widely used as pesticides in agriculture. However, the wide use of these pesticides inevitably causes serious drug resistance, it is therefore imperative to develop new avermectin and milbemycin analogs. The biosynthetic gene clusters of avermectin and milbemycin have been identified and the biosynthetic pathways have been elucidated. Combinatorial biosynthesis by domain swap provides an efficient strategy to generate chemical diversity according to the module polyketide synthase (PKS) assembly line.

Results: The substitution of aveDH2-KR2 located in avermectin biosynthetic gene cluster in the industrial avermectin-producing strain Streptomyces avermitilis NA-108 with the DNA regions milDH2-ER2-KR2 located in milbemycin biosynthetic gene cluster in Streptomyces bingchenggensis led to S. avermitilis AVE-T27, which produced ivermectin B1a with high yield of 3450 ± 65 μg/ml. The subsequent replacement of aveLAT-ACP encoding the loading module of avermectin PKS with milLAT-ACP encoding the loading module of milbemycin PKS led to strain S. avermitilis AVE-H39, which produced two new avermectin derivatives 25-ethyl and 25-methyl ivermectin (1 and 2) with yields of 951 ± 46 and 2093 ± 61 μg/ml, respectively. Compared to commercial insecticide ivermectin, the mixture of 25-methyl and 25-ethyl ivermectin (2:1 = 3:7) exhibited 4.6-fold increase in insecticidal activity against Caenorhabditis elegans. Moreover, the insecticidal activity of the mixture of 25-methyl and 25-ethyl ivermectin was 2.5-fold and 5.7-fold higher than that of milbemycin A3/A4 against C. elegans and the second-instar larva of Mythimna separate, respectively.

Conclusions: Two new avermectin derivatives 25-methyl and 25-ethyl ivermectin were generated by the domain swap of avermectin PKS. The enhanced insecticidal activity of 25-methyl and 25-ethyl ivermectin implied the potential use as insecticide in agriculture. Furthermore, the high yield and genetic stability of the engineered strains S. avermitilis AVE-T27 and AVE-H39 suggested the enormous potential in industrial production of the commercial insecticide ivermectin and 25-methyl/25-ethyl ivermectins, respectively.

No MeSH data available.


Related in: MedlinePlus