Sigma-E is required for the production of the antibiotic actinomycin in Streptomyces antibioticus.
The phsA gene encodes phenoxazinone synthase (PHS), which catalyses the penultimate step in the pathway for actinomycin biosynthesis in Streptomyces antibioticus. The phsA promoter strikingly resembles a putative Streptomyces sigma E cognate promoter, and purified E sigma E holoenzyme transcribed the phsA promoter in vitro. However, the phsA promoter was still active in an S. antibioticus sigE null mutant and the level of PHS activity was unaffected. Despite this, disruption of sigE blocked actinomycin production completely. The loss of actinomycin production correlated with a 10-fold decrease in the activity of actinomycin synthetase I, the enzyme which catalyses the activation of the precursor of the actinomycin chromophore.
Jones
G H
GH
Department of Genetics, John Innes Centre, Colney, Norwich, UK.
Paget
M S
MS
Chamberlin
L
L
Buttner
M J
MJ
D000595:Amino Acid Sequence; D003609:Dactinomycin / Q000096:biosynthesis*; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009713:Nucleotidyltransferases / Q000378:metabolism; D011401:Promoter Regions, Genetic; D012808:Sigma Factor / Q000235:genetics / Q000378:metabolism*; D013303:Streptomyces antibioticus / Q000201:enzymology* / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
D012808:Sigma Factor; D014157:Transcription Factors; C063202:sporulation-specific sigma factors; D003609:Dactinomycin; D009713:Nucleotidyltransferases; C075125:actinomycin synthetase I