Polyprenyl transferase; part of the gene cluster that mediates the biosynthesis of the meroterpenoids arthripenoids (PubMed:29797385). The pathway begins with the HR-PKS atnH that catalyzes two chain-extension steps to form a reduced triketide, which then primes the SAT domain in the NR-PKS atnG to initiate three more cycles of extension to give a linear hexaketide corresponding to the polyketide part of arthripenoids (PubMed:29797385). The FAD-dependent monooxygenase atnJ then performs an oxidative decarboxylation at C11 of the atnH/atnG product, via an electrophilic aromatic hydroxylation with concomitant ipso-decarboxylation (PubMed:29797385). The membrane-bound polyprenyl transferase atnF then introduces a farnesyl group before the FAD-dependent monooxygenase atnK functions as the first epoxidase on terminal C12'-C13' olefin, followed by a second epoxidation on C7'-C8' catalyzed by atnA (PubMed:29797385). The terpene cyclase/mutase atnI then initiates the sequential tricyclic ring formation through protonation of the terminal epoxide and catalyzes the regioselective and stereoselective 6/6/6-tricyclic ring formation (PubMed:29797385). The cytochrome P450 monooxygenase atnM is responsible for hydroxylating both C1' and C10' (Probable). The next steps may involve ketoreduction and acetyl transfer by the ketoreductase atnB and the acetyltransferase atnC, and lead to the production of arthripenoid B, the final biosynthetic product of the atn cluster (PubMed:29797385). The hydroquinone moiety in arthripenoid B is prone to undergo spontaneous oxidation to afford a benzoquinone compound, a key intermediate for generating structure diversity (Probable). For instance, addition of a cysteine followed by ring contraction gives arthripenoid A, tautomerization gives the main product arthripenoid C, addition of a molecular of water or amine affords arthripenoid D or E, respectively, and loss of one water forms arthripenoid F (Probable). Secondary metabolite biosynthesis; terpenoid biosynthesis. Abolishes the production of arthripenoids. Belongs to the UbiA prenyltransferase family.