Members of this family are cytochrome P450 enzymes that convert L-tryptophan into L-4-nitrotryptophan. In thaxtomin gene clusters, this enzyme (TxtE) uses nitric acid (NO) derived from arginine by the nitric oxide synthase TxtD, and O2, to perform the tryptophan nitration. L-4-nitrotryptophan is then used as a non-proteinogenic amino acid by non-ribosomal peptide synthases (NRPS).
Jiyao W et al.(2023). "The conserved domain database in 2023.",