Abstract:
Phylogenetic and structural analysis of P450 proteins fused to peroxidase/dioxygenase has not
been reported yet. We present phylogenetic and in silico structural analysis of the novel P450 fusion
family CYP5619 from the deadliest fish pathogenic oomycete, Saprolegnia diclina. Data-mining and
annotation of CYP5619 members revealed their unique presence in oomycetes. CYP5619 members
have the highest number of conserved amino acids among eukaryotic P450s. The highest number
of conserved amino acids (78%) occurred in the peroxidase/dioxygenase domain compared to the
P450 domain (22%). In silico structural analysis using a high-quality CYP5619A1 model revealed
that CYP5619A1 has characteristic P450 structural motifs including EXXR and CXG. However, the
heme-binding domain (CXG) in CYP5619 members was found to be highly degenerated. The in silico
substrate binding pattern revealed that CYP5619A1 have a high affinity to medium chain fatty acids.
Interestingly, the controlling agent of S. diclina malachite green was predicted to have the highest
binding affinity, along with linoleic acid. However, unlike fatty acids, none of the active site amino
acids formed hydrogen bonds with malachite green. The study’s results will pave the way for assessing
CYP5619A1’s role in S. diclina physiology, including the nature of malachite green binding.
