Biosynthesis of indigo in Escherichia coli expressing self-sufficient CYP102A from Streptomyces cattleya

Cytochrome P450 monooxygenases (CYP) are a superfamily of heme-thiolate proteins which catalyze the incorporation of oxygen atoms into substrates. Here, a self-sufficient CYP102A from Streptomyces cattleya (CYP102A_scat) was cloned, produced recombinantly in Escherichia coli strain BL21 (DE3), and the characteristic features were investigated. However, unlike other self-sufficient CYP102A enzymes that have been reported, CYP102A_scat was found to be able to catalyze intracellular hydroxylation of indole molecules with 3-C specific regioselectivity. Consequently, E. coli strains producing CYP102A_scat could synthesize approximately 1.0 g/L of indigo in LB media. Optimization of indigo synthesis was investigated through additional feeding of indole precursors such as glucose, l-tryptophan, and indole. Indigo production reached up to 3.8 ± 0.1 g/L by adding 20 μM of extracellular indole and 0.2 mM of l-tryptophan to the LB media. To our knowledge, this is a record and the highest yield achieved so far.