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Role of sgcR3 in positive regulation of enediyne antibiotic C-1027 production of Streptomyces globisporus C-1027

2009; BioMed Central; Volume: 9; Issue: 1 Linguagem: Inglês

10.1186/1471-2180-9-14

1471-2180

Lifei Wang, Yunfeng Hu, Yanjuan Zhang, Songmei Wang, Zhihui Cui, Yi Bao, Wei Jiang, Bin Hong,

Marine Sponges and Natural Products

Abstract Background C-1027, produced by Streptomyces globisporus C-1027, is one of the most potent antitumoral agents. The biosynthetic gene cluster of C-1027, previously cloned and sequenced, contains at least three putative regulatory genes, i.e. sgcR1 , sgcR2 and sgcR3 . The predicted gene products of these genes share sequence similarities to StrR, regulators of AraC/XylS family and TylR. The purpose of this study was to investigate the role of sgcR3 in C-1027 biosynthesis. Results Overexpression of sgcR3 in S. globisporus C-1027 resulted in a 30–40% increase in C-1027 production. Consistent with this, disruption of sgcR3 abolished C-1027 production. Complementation of the sgcR3 -disrupted strain R3KO with intact sgcR3 gene could restore C-1027 production. The results from real time RT-PCR analysis in R3KO mutant and wild type strain indicated that not only transcripts of biosynthetic structural genes such as sgcA1 and sgcC4 , but also putative regulatory genes, sgcR1 and sgcR2 , were significantly decreased in R3KO mutant. The cross-complementation studies showed that sgcR1R2 could functionally complement sgcR3 disruption in trans . Purified N-terminal His 10 -tagged SgcR3 showed specific DNA-binding activity to the promoter region of sgcR1R2 . Conclusion The role of SgcR3 has been proved to be a positive regulator of C-1027 biosynthesis in S. globisporus C-1027. SgcR3 occupies a higher level than SgcR1 and SgcR2 in the regulatory hierarchy that controls C-1027 production and activates the transcription of sgcR1 and sgcR2 by binding directly to the promoter region of sgcR1R2 .