Four HMM models for basidiomycete sesquiterpene cyclases

Sesquiterpene cyclases (STC) catalyze the removal of inorganic diphosphate (PPi) from farnesyl diphosphate, and the cyclization of the resulting carbocation. In fungi, STC that share a common ancestor catalyze a same cyclization mechanism: • clade 1 STC catalyze the 1,10-cyclization of (2E,6E)-FPP carbocation; • clade 2 STC catalyze the 1,10-cyclization of the (3R)-NPP carbocation; • clade 3 STC catalyze the 1,11 cyclization of (2E,6E)-FPP carbocation (trans-humulyl-type cyclases); • clade 4 STC catalyze the 1,6 or 1,7 cyclization of the (3R)-NPP carbocation. Here, we provide robust HMM models for the identification of STC genes in basidiomycete genomes. Their classification into one of the four clades will give indication for the prediction of their cyclisation mechanism.