2014.07.26【英译中】SCI 连载之十一

小妮丫头 (流火) 路人甲
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发表于:2014-07-26 00:28 [只看楼主] [划词开启]

2014.07.26【英译中】SCI 连载之十一


Applicability of rare earth elements to biotechnology

生物工程中稀土元素的应用

Despite the importance of rare earth elements (REEs) in the chemical industry, little is known about their biological effects in living cells. These elements, however, have recently been shown involved in the overproduction of antibiotics and in the activation of silent or poorly expressed genes in bacteria. The REEs consist of 17 elements, including scandium, yttrium, and the lanthanides (i.e., the 15 elements from lanthanum (La) to lutetium in the periodic table). Low concentrations (10– 100μM) of scandium (Sc) added to cultures of S. coelicolor (an actinorhodin producer), Streptomyces antibioticus (an actinomycin producer), and S. griseus(a streptomycin producer) were found to enhance antibiotic production 2–25-fold (Kawai et al.2007). The effects of Sc were exerted at the level of transcription of pathway-specific positive regulatory genes, as demonstrated by marked upregulation of act II-ORF4 in S. coelicolor. Notably, REEs were effective in activating silent and poorly expressed secondary metabolite biosynthetic genes in Streptomyces. That is, the addition to the medium of low concentrations of Sc or La activated the expression of nine genes, 2.5 - to 12-fold, belonging to nine secondary metabolite–biosynthetic gene clusters of S. coelicolor(Tanaka et al. 2010). HPLC analysis of ethyl acetate-extractable metabolites indicated that several compounds could be detected only in the REE-treated cultures. This approach, due to its feasibility, should facilitate the discovery of new biologically active compounds. The ability of REEs (especially Sc) to enhance enzyme production and secondary metabolism was also observed in B. subtilis. The addition of Sc to the growth medium stimulated the production of both α-amylase and bacilysin at the transcriptional level (Inaoka and Ochi2011).

尽管化学工厂中稀土元素(REEs)的重要性尽人皆知,只有很少一部分人知道它们在活体细胞中也有生物效应。这些元素现在被证实参与到抗生素的生产过剩当中,在细菌中沉默基因或者弱表达基因的激活当中也有参与。(REEs)17中元素组成,其中包括钪、钇和镧系元素(就是元素周期表中镧到镥的15个元素)。低浓度(10– 100μM)的钪(Sc)添加到S. coelicolor(能够产生放线紫红素)、Streptomyces antibioticus(能够产生放线菌素)和S. griseus(能够产生链霉素)当中,发现其抗生素产量增强2-25倍。钪元素在特异性阳性调节基因的转录水平上显示突出效应,正如S. coelicolor中标记的向上调节蛋白act II-ORF4证实的那样。特别是Streptomyces 中,REEs对激活沉默基因和弱表达次级代谢产物合成基因很有效果。确切地说,在培养基中添加低浓度的钪或者镧能够激活9个基因的表达2.5-12倍,这九种基因属于S. coelicolor中的次级代谢产物合成基因簇。通过HPLC分析乙酸乙酯萃取的代谢物发现,一些化合物只能在REE处理的培养基中检测到。由于它的可行性,这种方法能够帮助我们发现新的生物活性化合物的发现。在B. subtilis中同样观察到,REEs(尤其是钪)能够强化酶的产量和次级代谢系统。在生长培养基中添加钪能够激活转录水平的α-淀粉酶和杆菌溶素的产量。

 

REEs have long been known to have weak antimicrobial potency. Thus, it was possible to develop Sc-resistant mutants on plates containing Sc. As expected, actinorhodin overproducers (Ochi, unpublished results) and α-amylase overproducers (Inaoka and Ochi2012) were often found among the mutants of S. coelicolor and B. subtilis, respectively. In B. subtilis, a mutation in the uppS gene, which encodes the enzyme undecaprenyl pyrophosphate synthase, was responsible for the Sc resistance phenotype and α-amylase overproduction. This uppS86 mutation, however, did not affect the levels of amyE expression, suggesting that this mutation exerted its effects at the post-transcriptional level (Inaoka and Ochi2012). Thus, the mechanism by which α-amylase production was stimulated by the uppS86 mutation differed from that caused by the addition of Sc to the growth medium.

很长一段时间REEs都被认为其抗菌能力很弱。因此,我们可以在含有钪的平板上筛选钪抗性突变株。和期望一样的是,放线紫红素和α-淀粉酶的过量表达分别在S. coelicolor B. subtilis的突变株中经常被发现。B. subtilis中一株编码十一异戊烯焦磷酸盐合酶的uppS位点的突变就是负责耐钪显性和α-淀粉酶产量过剩。这种uppS突变株,并不会影响amyE的表达水平,说明这种突变株在转录后水平影响并不大。因此,α-淀粉酶产量受uppS86突变株影响的作用机制与生长培养基中添加钪引起的变化机制并不相同。

分类: 英语

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