UstYa family oxidase; part of the gene cluster that mediates the biosynthesis of the phomopsins, a group of hexapeptide mycotoxins which infects lupins and causes lupinosis disease in livestock. Within the pathway, phomYc catalyzes the desaturation of the Ile moiety into 2,3-dehydroisoleucine (dIle). The pathway starts with the processing of the precursor phomA by several endopeptidases including kexin proteases as well as the cluster-specific S41 family peptidase phomP1 and the oligopeptidase phomG to produce 10 identical copies of the hexapeptide Tyr-Val-Ile-Pro-Ile-Asp. After being excised from the precursor peptide, the core peptides are cyclized and modified post-translationally by enzymes encoded within the gene cluster. The timing and order of proteolysis of the phomA precursor and PTMs are still unknown. Two tyrosinase-like enzymes, phomQ1 and phomQ2, catalyze the chlorination and hydroxylation of Tyr, respectively. PhomYb, is proposed to be involved in the construction of the macrocyclic structure. The other 4 ustYa family proteins may be involved in PTMs that generate the unique structure of phomopsin A. PhomYa is required for the hydroxylation of C-beta of Tyr. PhomYc, phomYd, and phomYe are responsible for the biosynthesis of 2,3-dehydroisoleucine (dIle), 2,3-dehydroaspartic acid (dAsp), and 3,4-dehydroproline (dPro), respectively. While dIle formation by phomYc is indispensable for the installation of dAsp by phomYd, the order of the other PTMs have not been elucidated yet. Most of the biosynthetic enzymes likely have broad substrate specificity, and thus, there might be a metabolic grid from a precursor to phomopsin A. The enzyme(s) responsible for the biosynthesis of 3,4-dehydrovaline (dVal) have also not been identified yet. Finally, phomM acts as an S-adenosylmethionine-dependent alpha-N-methyltransferase that catalyzes two successive N-methylation reactions, converting N-desmethyl-phomopsin A to phomopsin A and phomopsin A further to an N,N-dimethylated congener called phomopsin E (Probable)