O-methyltransferase; part of the gene cluster that mediates the biosynthesis of KK-1, a novel cyclic decapeptide compound with potent antifungal activity (PubMed:29686660). The nonribosomal peptide synthetase (NRPS) catalyzes the elongation and cyclization of the decapeptide chain composed of 1 pipecolic acid residue (Pip), 1 alanine residue (Ala), 1 aspartic acid residue (Asp), 1 isoleucine residue (Ile), 1 glycine residue (Gly), 1 tyrosine residue (Tyr) and 4 valine residues (Val) (PubMed:29686660). The Asp, Ile and 3 Val residues are N-methylated by the 5 methyltransferase domains from the NRPS (found in modules 3, 5, 6, 7 and 9), whereas the Tyr residue is O-methylated, probably by the cluster encoded O-methyltransferase OMT (PubMed:29686660). The other tailoring enzymes from the cluster may be involved in further modifications leading to the synthesis of KK-1 (Probable). Secondary metabolite biosynthesis. Belongs to the class I-like SAM-binding methyltransferase superfamily. Cation-independent O-methyltransferase family.