Polyprenyl transferase; part of the gene cluster that mediates the biosynthesis of erinacines, cyathane-xylosides that show unique biological activities, including leishmanicidal activity, stimulating activity for nerve growth-factor synthesis, and agonistic activity toward the kappa opioid receptor (PubMed:31535864). The geranylgeranyl diphosphate (GGPP) synthase eriE catalyzes the first step in erinacines biosynthesis via conversion of farnesyl pyrophosphate and isopentyl pyrophosphate into geranylgeranyl pyrophosphate (GGPP) (PubMed:31535864). GGPP is then substrate of the diterpene cyclase eriG for the production of cyatha-3,12-diene (PubMed:28371074). EriG is unable to use geranyl diphosphate (GPP) or farnesyl diphosphate (FPP) as substrates (PubMed:28371074). The cytochrome P450 monooxygenase eriI then hydroxylates cyatha-3,12-diene at C-14 of the seven-membered ring to produce erinacol, which is further hydroxylated at C-15 by the cytochrome P450 monooxygenase eriC to yield cyathadiol (PubMed:31535864). The cytochrome P450 monooxygenase eriA then catalyzes C-11 hydroxylation in the presence of the short chain dehydrogenase/reductase (SDR) eriH, which leads to the production of cyathatriol (PubMed:31535864). The acetyltransferase eriL converts cyathatriol into 11-O-acetyl-cyathatriol (PubMed:31535864). The SDR eriH catalyzes further oxidation of 11-O-acetyl-cyathatriol into 1-O-acetylcyathin A3 (PubMed:31535864). Finally, the glycosyl transferase eriJ tranfers xylose from UDP-xylose onto C-14 of 11-O-acetyl-cyathatriol to form eracine Q (PubMed:31535864). EriJ is also able to convert 11-O-acetyl-cyathatriol to eracine Q2 by using UDP-D-glucose as cosubstrate, but at a lower rate (PubMed:31535864). In the absence of eriL and eriJ, the SDR eriH is able to convert cyathatriol to cyathin A3; this is likely a switching mechanism in the biosynthesis of cyathins (C-14 ketogroup)and erinacines (C-14 glycosylated group) (PubMed:31535864). The roles of the SDR eriB, the polyprenyl transferase eriF and the dehydrogenase eriK have still to be identified (Probable). EDTA completely blocks the reaction. Secondary metabolite biosynthesis. Belongs to the UbiA prenyltransferase family.