polR, a pathway-specific transcriptional regulatory gene, positively controls polyoxin biosynthesis in Streptomyces cacaoi subsp. asoensis.
The polyoxin (POL) biosynthetic gene cluster (pol) was recently cloned from Streptomyces cacaoi subsp. asoensis. A 3.3 kb DNA fragment carrying an obvious open reading frame (polR), whose deduced product shows sequence similarity to SanG of Streptomyces ansochromogenes and PimR of Streptomyces natalensis, was revealed within the pol gene cluster. Disruption of polR abolished POL production, which could be complemented by the integration of a single copy of polR into the chromosome of the non-producing mutant. The introduction of an extra copy of polR in the wild-type strain resulted in increased production of POLs. The transcription start point (tsp) of polR was determined by S1 mapping. Reverse transcriptase PCR experiments showed that PolR is required for the transcription of 18 structural genes in the pol gene cluster. Furthermore, we showed that polC and polB, the respective first genes of two putative operons (polC-polQ2 and polA-polB) consisting of 16 and 2 of these 18 genes, have similar promoter structures. Gel retardation assays indicated that PolR has specific DNA-binding activity for the promoter regions of polC and polB. Our data suggest that PolR acts in a positive manner to regulate POL production by activating the transcription of at least two putative operons in the pol gene cluster.
Li
Rui
R
State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.
Xie
Zhoujie
Z
State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.
Tian
Yuqing
Y
State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.
Yang
Haihua
H
State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.
Chen
Wenqing
W
Laboratory of Microbial Metabolism and School of Life Science and Biotechnology, Shanghai Jiaotong University, Shanghai 200030, China.
You
Delin
D
Laboratory of Microbial Metabolism and School of Life Science and Biotechnology, Shanghai Jiaotong University, Shanghai 200030, China.
Liu
Gang
G
State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.
Deng
Zixin
Z
Laboratory of Microbial Metabolism and School of Life Science and Biotechnology, Shanghai Jiaotong University, Shanghai 200030, China.
Tan
Huarong
H
State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China.
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000502:physiology; D001483:Base Sequence; D004269:DNA, Bacterial / Q000032:analysis / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial / Q000502:physiology*; D005816:Genetic Complementation Test; D008969:Molecular Sequence Data; D005810:Multigene Family; D011401:Promoter Regions, Genetic; D011741:Pyrimidine Nucleosides / Q000096:biosynthesis; D013302:Streptomyces / Q000235:genetics / Q000378:metabolism*; D024363:Transcription Initiation Site; D015854:Up-Regulation
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D011741:Pyrimidine Nucleosides; C002457:polyoxin