Characterization of representative rpoB gene mutations leading to a significant change in toyocamycin production of Streptomyces diastatochromogenes 1628
Characterization of representative rpoB gene mutations leading to a significant change in toyocamycin production of Streptomyces diastatochromogenes 1628
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第 1628 章
DOI：
10.1007/s10295-015-1732-4
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发表时间：
2016-04-01
影响因子：
3.4
通讯作者：
Yu, Xiaoping
中科院分区：
文献类型：
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作者：
Ma, Zheng;Luo, Shuai;Yu, Xiaoping
在链霉菌中，对参与转录或翻译过程的酶进行修饰是一种增加次生代谢物产量的有趣方法。然而，对于产生核苷类抗生素的菌株，这些方法的应用尚未得到广泛的描述。核苷类抗生素toyocamycin （TM）是由异色链霉菌（Streptomyces disastatochromogenes） 1628产生的。为了提高S. diastatochromogenes 1628的TM产量，将该菌株散布在耐利福霉素（rifamycin-resistant, Rifr）培养基上。在编码RNA聚合酶β-亚基的rpoB基因突变中获得了几个自发突变体。在所有rfr突变体中，检测到增加TM产量的突变体的频率为7.5%。含有氨基酸取代His437Arg的突变体1628-T15是产生TM的最佳菌株，比野生型菌株增加4.5倍。产孢能力最差的是突变体1628-T62，其产孢能力也较差。采用RT-PCR方法研究了TM生物合成基因toyG在亲本菌株以及突变体1628-T15和1628-T62中的转录水平。突变体1628- t15的toyG转录水平高于亲本1628，而突变体1628- t62的toyG转录水平则明显低于亲本1628。在突变株1628-T62中，形态分化所需的adpA sd基因的表达量也明显降低。我们的研究还表明，在rpoB中引入突变是提高TM生产的有效策略，TM是一种重要的核苷类抗生素。
Modification of enzymes involved in transcription- or translation-processes is an interesting way to increase secondary metabolite production in Streptomycetes. However, application of such methods has not been widely described for strains which produce nucleoside antibiotics. The nucleoside antibiotic toyocamycin (TM) is produced by Streptomyces diastatochromogenes 1628. For improving TM production in S. diastatochromogenes 1628, the strain was spread on rifamycin-resistant (Rifr) medium. Several spontaneous mutants were obtained with mutations in the rpoB gene which encodes a RNA polymerase β-subunit. The mutants which showed increased TM production were detected at a frequency of 7.5 % among the total Rifr mutants. Mutant 1628-T15 harboring amino acid substitution His437Arg was the best TM producer with a 4.5-fold increase in comparison to that of the wild-type strain. The worst producer was mutant 1628-T62 which also showed a poor sporulation behavior. RT-PCR was performed to study the transcription levels of the TM biosynthetic gene toyG in the parental strain as well as in mutants 1628-T15 and 1628-T62. The transcriptional level of toyG was higher in mutant 1628-T15 than that in parental strain 1628, while much lower in mutant 1628-T62. In mutant strain 1628-T62 the expression of adpA sd gene, which is required for morphological differentiation, was also much lower. Our studies also indicate that the introduction of mutations into rpoB is an effective strategy to improve the production of TM which is an important nucleoside antibiotic.