Biosynthetic studies on teleocidins in Streptomyces

Area of Science:

• Biochemistry
• Molecular Biology
• Natural Product Biosynthesis

Background:

• Teleocidin B is a potent protein kinase C activator with a unique indolactam-terpenoid structure.
• Understanding its biosynthesis is crucial for natural product drug discovery.
• Streptomyces blastmyceticus is the producing organism.

Purpose of the Study:

• To identify and characterize the biosynthetic genes responsible for teleocidin B production.
• To elucidate the enzymatic mechanisms underlying teleocidin B formation, including prenylation and cyclization.
• To explore the potential for generating novel teleocidin analogs through structure-based engineering.

Main Methods:

• Identification of teleocidin B biosynthetic gene cluster (tleABC genes and tleD).
• In vivo and in vitro enzymatic assays to determine the functions of TleD and TleC.
• X-ray crystallography to determine the structures of prenylation enzymes.
• Structure-based mutagenesis to create novel teleocidin analogs.

Main Results:

• The tleD gene, encoding a C-methyltransferase, is located outside the main tleABC cluster.
• TleD catalyzes C-methylation of the prenyl chain and initiates indole-fused cyclic terpene formation.
• This represents the first report of terpene cyclization initiated by prenyl double bond C-methylation.
• TleC performs geranylation at the C-7 position of the indole ring in a reverse manner.
• X-ray crystallography and mutagenesis provided structural insights and generated novel prenylated indolactams.

Conclusions:

• The study reveals a novel biosynthetic pathway for teleocidin B involving unique enzymatic steps.
• The findings provide a foundation for engineering teleocidin biosynthesis to produce novel analogs.
• This research contributes to the understanding of natural product biosynthesis and drug discovery.