The LuxR family members GdmRI and GdmRII are positive regulators of geldanamycin biosynthesis in Streptomyces hygroscopicus 17997
The LuxR family members GdmRI and GdmRII are positive regulators of geldanamycin biosynthesis in Streptomyces hygroscopicus 17997
复制标题
DOI：
10.1007/s00203-007-0346-2
复制
发表时间：
2008-05-01
影响因子：
2.8
通讯作者：
Wang, Yiguang
中科院分区：
文献类型：
--
作者：
He, Weiqing;Lei, Jian;Wang, Yiguang
最近对格尔德霉素后聚酮合酶（PKS）修饰基因簇的DNA区域进行测序，发现存在两个调控基因：gdmRI（2，907 bp）和gdmRII（2，766 bp）。gdmRI和gdmRII（分别为968和921个氨基酸残基）的推导产物被鉴定为LuxR转录调控蛋白的同源物。通过吸水链霉菌17997基因组中gdmRI或gdmRII的基因置换失活导致格尔德霉素生产完全丧失。互补质粒携带gdmRI或gdmRII恢复格尔德霉素生产，这表明这两个调节基因的产品是积极的调节剂，需要格尔德霉素生物合成。在Delta gdmRII突变体中检测到gdmRI转录物，并且在Delta gdmRI突变体中检测到gdmRII，表明这两个基因独立转录并且不相互调节。通过格尔德霉素生物合成基因的RT-PCR的基因表达分析的时间过程表明，转录的gdmRI和gdmRII与参与聚酮生物合成的基因相关，但不与后PKS修饰基因gdmN，其转录开始较早。gdmRI或gdmRII基因干扰物不转录聚酮生物合成相关基因pks、gdmF和gdnA-O-P，但转录gdmN。这些结果表明，gdmRI和gdmRII是控制格尔德霉素生物降解中聚酮生物合成基因的途径特异性正调控因子，但不是PKS修饰后基因gdmN。
The recent sequencing of the DNA region of the geldanamycin post-polyketide synthase (PKS) modification gene clusters revealed the presence of two regulatory genes: gdmRI (2,907 bp) and gdmRII (2,766 bp). The deduced products of gdmRI and gdmRII (968 and 921 amino acid residues, respectively) were identified as homologues of the LuxR transcriptional regulatory proteins. Inactivation by gene replacement of gdmRI or gdmRII in the Streptomyces hygroscopicus 17997 genome resulted in a complete loss of geldanamycin production. Complementation by a plasmid carrying gdmRI or gdmRII restored geldanamycin production, suggesting that the products of these two regulatory genes are positive regulators that are required for geldanamycin biosynthesis. The gdmRI transcript was detected in the Delta gdmRII mutant, and the gdmRII was detected in the Delta gdmRI mutant, indicating that the two genes are transcribed independently and do not regulate each other. Time course of gene expression analysis by RT-PCR of the geldanamycin biosynthetic genes showed that the transcription of gdmRI and gdmRII correlates with that of genes involved in polyketide biosynthesis, but not with the post-PKS modification gene gdmN, whose transcription is initiated earlier. gdmRI or gdmRII gene disruptants did not transcribe the polyketide biosynthetic related genes pks, gdmF, and gdnA-O-P, but did trancribe gdmN. These results demonstrated that gdmRI and gdmRII are pathway-specific positive regulators that control the polyketide biosynthetic genes in geldanamycin biosynthsis, but not the post-PKS modification gene, gdmN.