Part:BBa_K4229001

Fre (NAD(P)H-flavin reductase)

The flavin-reducing enzyme Fre catalyzes the reduction of soluble flavins by reduced pyridine nucleotides (UniProt ID:P0AEN1).

Fre is one of four enzymes we used in our project to produce indigo and indirubin. In our pathway it accelerates the recycling of the cofactor NADPH, and adds more FADH2 for the enzyme XiaI (Figure 1).

Figure 1: Schematic representation of the indigo/indirubin pathway. L-Tryptophan is imported by the membrane protein TnaB (low affinity tryptophan permease). L-tryptophan is cleaved into indole, NH4+ and pyruvate by the Tryptophanase TnaA. The reaction continues by the hydroxylation of indole through XiaI. To enhance the effectivity of this enzyme, the NAD(P)H-flavin reductase provides XiaI with FADH2 by adding Hydrogen to FAD. Finally, indole is transformed to either 3-Hydroxyindole or 2-Hydroxyindole. These two substances spontaneously react to 3-Oxindole and 2-Oxindole through the secession of hydrogen from the OH-group. Through spontaneous dimerization indigo and indirubin are formed. Graphic adapted from [1].

References:
[1] H. Yin et al., “Efficient Bioproduction of Indigo and Indirubin by Optimizing a Novel Terpenoid Cyclase XiaI in Escherichia coli,” ACS Omega, vol. 6, no. 31, pp. 20569–20576, 2021, doi: 10.1021/acsomega.1c02679.

Sequence and Features

Assembly Compatibility:

• 10
  COMPATIBLE WITH RFC[10]
• 12
  COMPATIBLE WITH RFC[12]
• 21
  COMPATIBLE WITH RFC[21]
• 23
  COMPATIBLE WITH RFC[23]
• 25
  COMPATIBLE WITH RFC[25]
• 1000
  INCOMPATIBLE WITH RFC[1000]

  Illegal SapI.rc site found at 304
  Illegal SapI.rc site found at 424