O-Mevalon transferase yanI; part of the gene cluster that mediates the biosynthesis of yanuthone D, a fungal isoprenoid epoxycyclohexenone that acts as an antibiotic against fungi and bacteria (PubMed:24684908). The first step of the pathway is the synthesis of 6-methylsalicylic acid (6-MSA) by the polyketide synthase yanA (PubMed:24684908). 6-MSA is then converted to m-cresol by the decarboxylase yanB (PubMed:24684908). The cytochrome P450 monooxygenase yanC then catalyzes the oxidation of m-cresol to toluquinol (PubMed:24684908). Epoxidation of toluquinol is then performed by the short chain dehydrogenase yanD, with the help of yanE, and a further prenylation by yanG leads to 7-deacetoxyyanuthone A (PubMed:24684908). The next step is the hydroxylation of C-22 of 7-deacetoxyyanuthone A by the cytochrome P450 monooxygenase yanH to yield 22-deacetylyanuthone A (PubMed:24684908). O-Mevalon transferase yanI then attaches mevalon to the hydroxyl group of 22-deacetylyanuthone A to produce yanuthone E (PubMed:24684908). Finally, the FAD-dependent monooxygenase yanF oxidizes the hydroxyl group at C15 of yanuthone E to form yanuthone D (PubMed:24684908). Furthermore, several branching points in the pathway lead to the production of yanuthones F and G from 7-deacetoxyyanuthone A; yanuthones H and I from 22-deacetylyanuthone A; and yanuthone J from yanuthone E (PubMed:24684908). Secondary metabolite biosynthesis; terpenoid biosynthesis. Loses the ability to produce yanuthone D, but accumulates 7-deacetoxyyanuthone A and 22-deacetylyanuthone A as well as two derivatives called yanuthone H and yanuthone I (PubMed:24684908). Yanuthone D is an antibiotic against C.albicans, methicillin-resistant S.aureus (MRSA), and vancomycin-resistant Enterococcus (PubMed:11031048).