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ktnB

Gene
ktnB
Protein
O-methyltransferase kntB
Organism
Aspergillus niger (strain CBS 513.88 / FGSC A1513)
Length
413 amino acids
Function
Non-reducing polyketide synthase; part of the gene cluster that mediates the biosynthesis of the bicoumarin kotanin (PubMed:22945023, PubMed:26389790). The non-reducing polyketide synthase ktnS first catalyzes the formation of the pentaketidic 4,7-dihydroxy-5-methylcoumarin from acetyl coenzyme A and 4 malonyl coenzyme A molecules (PubMed:17315249, PubMed:22945023). Further O-methylation by ktnB leads to the formation of 7-demethylsiderin (PubMed:17315249, PubMed:22945023, PubMed:26389790). Then, an oxidative phenol coupling catalyzed by the cytochrome P450 monooxygenase ktnC forms the 8,8'-dimer P-orlandin via dimerization the monomeric precursor, 7-demethylsiderin (PubMed:26389790). P-orlandin is subsequently O-methylated in a stepwise fashion to demethylkotanin and kotanin (PubMed:22945023).
Similarity
Belongs to the class I-like SAM-binding methyltransferase superfamily. Cation-independent O-methyltransferase family.
Mass
46.523 kDa
Sequence
MTYPEEIDEYSLIQNGLKSLNEAAQRCQQTKHSSQDSSIEGCSARQSARDELVLEALKFLQIAQGPIDAAATCYERTAHLASVRALLEMGVFEALPTGRVSRRTEELARELNVDESLLARLLRNSSLYGPFEETGPGQYRHTPFSEAYLRPEIRGMFRFAMDDHMPAHLKLHEFLQRNGWQEPSSTTDNPYTYAHKTNGKSMFDNLSEKPERMKAFNNGMTVQAMTPLWMIDLFPWRSLAQLKPTAGQVLAVDIGGGKGKAISRIRSFCNGLPGRYILQDQEHVVKSVEGSLDPSIERMAYNFFTEQPIRGAVTYLIRRCLHNWPQDSVVCILQNIAAAMEPGKSRLLIEEIVVPAEKAGVEEGWMDMIMMSLGAKQRTLKEWEMVLGLAGLEVKKVYQIPGNCHGLIEAWLK