A Tryptophan 6-Halogenase and an Amidotransferase Are Involved in Thienodolin Biosynthesis

The biosynthetic gene cluster for the plant growth‐regulating compound thienodolin was identified in and cloned from the producer organism Streptomyces albogriseolus MJ286‐76F7. Sequence analysis of a 27 kb DNA region revealed the presence of 21 ORFs, 14 of which are involved in thienodolin biosynth...

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Bibliographic Details
Published in:Chembiochem : a European journal of chemical biology 2014-05, Vol.15 (7), p.1011-1020
Main Authors: Milbredt, Daniela, Patallo, Eugenio P., van Pée, Karl-Heinz
Format: Article
Language:English
Subjects:
amidotransferases
Amino Acid Oxidoreductases - genetics
Amino Acid Oxidoreductases - metabolism
Bacteriology
Biosynthesis
Cloning, Molecular
Genes
halogenation
Indoles - chemistry
Indoles - metabolism
Multigene Family
natural products
Open Reading Frames
Oxidoreductases - genetics
Oxidoreductases - metabolism
Recombinant Proteins - biosynthesis
Recombinant Proteins - genetics
Streptomyces - enzymology
Streptomyces - genetics
thienodolin
Thiophenes - chemistry
Thiophenes - metabolism
tryptophan halogenases
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Summary:The biosynthetic gene cluster for the plant growth‐regulating compound thienodolin was identified in and cloned from the producer organism Streptomyces albogriseolus MJ286‐76F7. Sequence analysis of a 27 kb DNA region revealed the presence of 21 ORFs, 14 of which are involved in thienodolin biosynthesis. Three insertional inactivation mutants were generated in the sequenced region to analyze their involvement in thienodolin biosynthesis and to functionally characterize specific genes. The gene inactivation experiments together with enzyme assays with enzymes obtained by heterologous expression and feeding studies showed that the first step in thienodolin biosynthesis is catalyzed by a tryptophan 6‐halogenase and that the last step is the formation of a carboxylic amide group catalyzed by an amidotransferase. The results led to a hypothetical model for thienodolin biosynthesis. The skeleton lives: Thienodolin shows concentration‐dependent growth‐regulating activity towards rice seedlings. This secondary metabolite has a thienoindole skeleton chlorinated in the 6‐position of the indole ring. Here we present insights into the biosynthesis of the alkaloid, including the complete gene cluster and elucidation of two biosynthetic steps.
ISSN:1439-4227
1439-7633
DOI:10.1002/cbic.201400016