Role of sgcR3 in positive regulation of enediyne antibiotic C-1027 production of Streptomyces globisporus C-1027.
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 His10-tagged SgcR3 showed specific DNA-binding activity to the promoter region of sgcR1R2.


CONCLUSIONS
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.
Wang
Lifei
L
Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100050, PR China. lifeiwang2002@hotmail.com
Hu
Yunfeng
Y
Zhang
Yanjuan
Y
Wang
Songmei
S
Cui
Zhihui
Z
Bao
Yi
Y
Jiang
Wei
W
Hong
Bin
B
D000617:Aminoglycosides / Q000096:biosynthesis*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D053281:Enediynes; D015964:Gene Expression Regulation, Bacterial; D020868:Gene Silencing; D005816:Genetic Complementation Test; D009154:Mutation; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D013302:Streptomyces / Q000235:genetics / Q000378:metabolism*
D000617:Aminoglycosides; D001426:Bacterial Proteins; D053281:Enediynes; C058024:C 1027