Thirty-two actinomycetes strains were isolated from sediment samples from 12 different sites at Lagos Lagoon and identified using standard physiological and biochemical procedures as well as 16S rDNA gene sequence ana...Thirty-two actinomycetes strains were isolated from sediment samples from 12 different sites at Lagos Lagoon and identified using standard physiological and biochemical procedures as well as 16S rDNA gene sequence analysis. Secondary metabolites were extracted from the strains and their anticancer activity on the K562 (Human acute myelocytic leukemia), HeLa (cervical carcinoma), AGS (Human gastric), MCF- 7 (breast adenocarcinoma) and HL-60 (Human acute promyelocytic leukemia) cell lines was determined. The metabolic extracts exhibited cytotoxicity with IC50 values ranging from 0.030 mg/mL to 4.4 mg/mL. The Streptomyces bingchenggensis ULS14 extract was cytotoxic against all the cell lines tested. The bioactivity-guided extraction and purification of the metabolic extracts from this strain yielded two purified anticancer compounds: ULDF4 and ULDF5. The structures of the extracted compounds were determined using spectroscopic analyses, including electrospray ionization mass spectrophotometer and nuclear magnetic resonance (1 Dimensional and 2 Dimensional), and were shown to be structurally similar to staurosporine and kigamicin. The IC50 of ULDF4 and ULDF5 against the HeLa cell line was 0.034 mg/mL and 0.075 mg/mL, respectively. This study is the first to reveal the anticancer potential of actinomycetes from Lagos Lagoon, which could be exploited for therapeutic purposes.展开更多
Streptomyces can produce numerous antibiotics and many other bioactive compounds.Recently,the molecular mechanisms of transcriptional regulators in control of antibiotic production by influencing the expression of bio...Streptomyces can produce numerous antibiotics and many other bioactive compounds.Recently,the molecular mechanisms of transcriptional regulators in control of antibiotic production by influencing the expression of biosynthetic gene clusters(BGCs)have been extensively studied.However,for regulators that affect both antibiotic production and cell growth,the way to influence antibiotic production may be diverse,but related studies are limited.Here,based on time-course transcriptome analysis,a four-component system,SbrH1-R,consisting of the two-component system SbrKR(SBI_03479/3478)and two hypothetical proteins SbrH1(SBI_03481)and SbrH2(SBI_03480)potentially related with the biosynthesis of milbemycins was identified in Streptomyces bingchenggensis BC-101-4.Deletion of sbrH1-R resulted in weakened cell growth but a 110%increase of milbemycin production compared with that in BC-101-4.Comparative transcriptome analyses of the sbrH1-R mutant and BC-101-4 revealed that SbrH1-R not only indirectly represses milbemycin BGC expression,but also inhibits milbemycin production by modulating expression levels of genes related to precursor supply and antibiotic efflux.Further genetic experiments identified several new targets,including five precursor supply-associated reactions/pathways(e.g.,the reaction from pyruvate to acetyl-CoA,the reaction from acetyl-CoA to citrate,the fatty acidβ-oxidation process,and the branched chain amino acid and phenylalanine acid degradation pathways)and a milbemycin exporter system(MilEX2)that can be engineered for milbemycin overproduction.These results shed new light on the understanding of regulation of milbemycin biosynthesis and provide useful targets for future metabolic engineering of the native host to improve milbemycin production.展开更多
基金supported by the University of Lagos Central Research Committee Grant (Grant No: ULCRC 2012/08)
文摘Thirty-two actinomycetes strains were isolated from sediment samples from 12 different sites at Lagos Lagoon and identified using standard physiological and biochemical procedures as well as 16S rDNA gene sequence analysis. Secondary metabolites were extracted from the strains and their anticancer activity on the K562 (Human acute myelocytic leukemia), HeLa (cervical carcinoma), AGS (Human gastric), MCF- 7 (breast adenocarcinoma) and HL-60 (Human acute promyelocytic leukemia) cell lines was determined. The metabolic extracts exhibited cytotoxicity with IC50 values ranging from 0.030 mg/mL to 4.4 mg/mL. The Streptomyces bingchenggensis ULS14 extract was cytotoxic against all the cell lines tested. The bioactivity-guided extraction and purification of the metabolic extracts from this strain yielded two purified anticancer compounds: ULDF4 and ULDF5. The structures of the extracted compounds were determined using spectroscopic analyses, including electrospray ionization mass spectrophotometer and nuclear magnetic resonance (1 Dimensional and 2 Dimensional), and were shown to be structurally similar to staurosporine and kigamicin. The IC50 of ULDF4 and ULDF5 against the HeLa cell line was 0.034 mg/mL and 0.075 mg/mL, respectively. This study is the first to reveal the anticancer potential of actinomycetes from Lagos Lagoon, which could be exploited for therapeutic purposes.
基金This work was financially supported by National Natural Science Foundation of China(31872936,31972291,and 31972348).
文摘Streptomyces can produce numerous antibiotics and many other bioactive compounds.Recently,the molecular mechanisms of transcriptional regulators in control of antibiotic production by influencing the expression of biosynthetic gene clusters(BGCs)have been extensively studied.However,for regulators that affect both antibiotic production and cell growth,the way to influence antibiotic production may be diverse,but related studies are limited.Here,based on time-course transcriptome analysis,a four-component system,SbrH1-R,consisting of the two-component system SbrKR(SBI_03479/3478)and two hypothetical proteins SbrH1(SBI_03481)and SbrH2(SBI_03480)potentially related with the biosynthesis of milbemycins was identified in Streptomyces bingchenggensis BC-101-4.Deletion of sbrH1-R resulted in weakened cell growth but a 110%increase of milbemycin production compared with that in BC-101-4.Comparative transcriptome analyses of the sbrH1-R mutant and BC-101-4 revealed that SbrH1-R not only indirectly represses milbemycin BGC expression,but also inhibits milbemycin production by modulating expression levels of genes related to precursor supply and antibiotic efflux.Further genetic experiments identified several new targets,including five precursor supply-associated reactions/pathways(e.g.,the reaction from pyruvate to acetyl-CoA,the reaction from acetyl-CoA to citrate,the fatty acidβ-oxidation process,and the branched chain amino acid and phenylalanine acid degradation pathways)and a milbemycin exporter system(MilEX2)that can be engineered for milbemycin overproduction.These results shed new light on the understanding of regulation of milbemycin biosynthesis and provide useful targets for future metabolic engineering of the native host to improve milbemycin production.
