The regulatory genes involved in spiramycin and bitespiramycin biosynthesis
The regulatory genes involved in spiramycin and bitespiramycin biosynthesis
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螺旋霉素和比特螺旋霉素生物合成涉及的调控基因
DOI：
10.1016/j.micres.2020.126532
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发表时间：
2020
影响因子：
6.7
通讯作者：
Weiqing He
中科院分区：
文献类型：
--
作者：
Jianlu Dai;Yiguang Wang;Juanjuan Liu;Weiqing He
比特螺旋霉素（biotechnologicalspiramycin，Bsm）是由螺旋链霉菌WSJ-1整合外源基因产生的一种新型16元大环内酯类抗生素。 Bsm生物合成基因簇由两部分组成：螺旋霉素生物合成基因簇（92 kb）和两个外源基因，包括来自耐热链球菌的4'-O-异戊酰转移酶基因（ist）和正调控基因（acyB2）。通过螺旋霉素基因中的序列分析，鉴定了四个假定的调控基因：bsm2、bsm23、bsm27和bsm42螺旋霉素的bsm23或bsm42的失活消除了螺旋霉素的产生，而bsm2和bsm27的缺失并没有消除与bsm42基因同源的TheacyB2基因，不能恢复Δbsm42突变体的螺旋霉素的产生。螺旋霉素的产生，但bsm23的过表达抑制了其在Δbsm23中的产生，并且通过电泳迁移率变动分析表明Bsm23参与了bsm42和acyB2的表达调节，从提高的4'-异戊酰螺旋霉素产量推断，bsm42基因也是螺旋霉素表达的正调节因子。 lividansTK24生物转化试验，但添加bsm23减少了4ʹʹ-异戊酰螺旋霉素的产生。这些结果表明，Bsm42 是螺旋霉素或 Bsm 生物合成的途径特异性激活剂，但单独过度表达 Bsm23 不利于产生这些抗生素，尽管 Bsm23 对于螺旋霉素产生的正调节至关重要。
Bitespiramycin (biotechnologicalspiramycin, Bsm) is a new 16-membered macrolide antibiotic produced byStreptomyces spiramyceticusWSJ-1 integrated exogenous genes. The gene cluster for Bsm biosynthesis consists of two parts: spiramycin biosynthetic gene cluster (92 kb) and two exogenous genes including 4"-O-isovaleryltransferase gene (ist)and a positive regulatory gene (acyB2) fromS. thermotolerans. Four putative regulatory genes,bsm2,bsm23,bsm27andbsm42, were identified by sequence analysis in the spiramycin gene cluster. The inactivation ofbsm23orbsm42inS. spiramyceticuseliminated spiramycin production, while the deletion ofbsm2andbsm27did not abolish spiramycin biosynthesis. TheacyB2gene, homologous withbsm42gene, cannot recover the spiramycin production in Δbsm42mutant. The high expression ofbsm42significantly increased the spiramycin production, but overexpression ofbsm23inhibited its production in Δbsm23and wild-type strain. Bsm23 was shown to be involved in the regulation of the expression ofbsm42andacyB2by electrophoretic mobility shift assays. Thebsm42gene was also positive regulator foristexpression inferred from the improved yield of 4"-isovalerylspiramycins in theS. lividansTK24 biotransformation test, but addingbsm23decreased the production of 4ʹʹ-isovalerylspiramycins. These results demonstrated Bsm42 was a pathway-specific activator for spiramycin or Bsm biosynthesis, but overexpression of Bsm23 alone was adverse to produce these antibiotics although Bsm23 was essential for positive regulation of spiramycin production.