Fig. 1

Schematic diagram of protoilludene biosynthesis via mevalonate (MVA) pathway. Protoilludene biosynthesis pathway is divided into three portions: MvU (acetyl-CoA to mevalonate), MvL (mevalonate to IPP and DMAPP) and AO (IPP and DMAPP to protoilludene). MvU portion is composed of MvaE (HMG-CoA reductase/acetyl-CoA acetyltransferase) and MvaS (HMG-CoA synthase). MvL portion is comprised of MvaK1 (mevalonate kinase), MvaK2 (phosphomevalonate kinase), MvaD (diphosphomevalonate decarboxylase) and IDI (IPP isomerase). AO portion consists of IspA (FPP synthase) and OMP7 (protoilludene synthase). Illudins, marasmanes and melleolides are protoilludene derivatives. Pathway intermediates for protoilludene synthesis are as follows: A-CoA, acetyl-CoA; AA-CoA, acetoacetyl-CoA; HMG-CoA, hydroxymethylglutaryl-CoA; MVAP, phosphomevalonate; MVAPP, diphosphomevalonate; IPP, isopentenyl diphosphate; DMAPP, dimethylallyl diphosphate; and FPP, farnesyl diphosphate. Solid and dashed arrows indicate the identified and unidentified reactions, respectively