The tyrosine degradation gene hppD is transcriptionally activated by HpdA and repressed by HpdR in Streptomyces coelicolor, while hpdA is negatively autoregulated and repressed by HpdR.
Streptomyces coelicolor produces a brown pigment on nutrient-limited agar medium (Tyr-PM) using l-tyrosine as the sole nitrogen and carbon source. The pigment production is associated with the second step of l-tyrosine catabolism catalysed by 4-hydroxyphenylpyruvate dioxygenase (HppD), which converts 4-hydroxyphenylpyruvate (4HPP) to 2, 5-dihydroxyphenylacetate (homogentisate) to provide the carbon and energy substrates for the growth of S. coelicolor on Tyr-PM. An hppD mutant did not produce brown pigment, and its normal growth was impaired on Tyr-PM. hpdA and hpdR, located close to hppD, were identified as activator and repressor genes for hppD transcription in the presence of tyrosine. hpdA, divergently transcribed from hppD, is negatively autoregulated in the absence of tyrosine, whereas it is repressed by both its own protein and HpdR in the presence of tyrosine. Electrophoretic mobility shift assays and footprinting experiments showed that HpdA and HpdR each bind to an overlapping region spanning the promoters of both hppD and hpdA, and that 4HPP, instead of tyrosine, is the specific ligand modulating the binding patterns and footprints of HpdA and HpdR on the hppD-hpdA promoter region. These results suggested that the transcription of hppD is subject to coarse and fine control by a complex regulatory system.
Yang
Haihua
H
State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Science, Beijing 100101, China.
Wang
Linqi
L
Xie
Zhoujie
Z
Tian
Yuqing
Y
Liu
Gang
G
Tan
Huarong
H
D001426:Bacterial Proteins / Q000235:genetics*; D001483:Base Sequence; D018533:Biomass; D002876:Chromosomes, Bacterial; D018983:DNA Footprinting; D015342:DNA Probes / Q000378:metabolism; D015536:Down-Regulation / Q000187:drug effects / Q000235:genetics*; D005502:Food; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D005798:Genes, Bacterial; D008969:Molecular Sequence Data; D010641:Phenotype; D010667:Phenylpyruvic Acids / Q000494:pharmacology; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding / Q000187:drug effects; D012097:Repressor Proteins / Q000378:metabolism*; D048372:Streptomyces coelicolor / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development; D015533:Transcriptional Activation / Q000187:drug effects / Q000235:genetics; D014443:Tyrosine / Q000378:metabolism*
D001426:Bacterial Proteins; D015342:DNA Probes; D010667:Phenylpyruvic Acids; D012097:Repressor Proteins; C010590:4-hydroxyphenylpyruvic acid; D014443:Tyrosine