Beta-cyclopiazonate dehydrogenase; part of the gene cluster that mediates the biosynthesis of the fungal neurotoxin cyclopiazonic acid (CPA), a nanomolar inhibitor of Ca(2+)-ATPase with a unique pentacyclic indole tetramic acid scaffold (PubMed:21608094). The hybrid two module polyketide synthase-nonribosomal peptide synthetase (PKS-NRPS) cpaS incorporates acetyl-CoA, malonyl-CoA, and tryptophan (Trp) and utilizes a C-terminal redox-incompetent reductase domain to make and release the tryptophan tetramic acid, cyclo-acetoacetyl-L-tryptophan (c-AATrp), as the first intermediate in the pathway. CpaS catalyzes a Dieckmann-type cyclization on the N-acetoacetyl-Trp intermediate bound in thioester linkage to the phosphopantetheinyl arm of the T domain to form and release c-AATrp (PubMed:19663400). CpaD than regiospecifically dimethylallylates c-AATrp to form beta-cyclopiazonic acid. CpaD discriminates against free Trp but accepts tryptophan-containing thiohydantoins, diketopiperazines, and linear peptides as substrates for C4-prenylation and also acts as regiospecific O-dimethylallyltransferase (DMAT) on a tyrosine-derived tetramic acid (PubMed:21608094, PubMed:19877600). The beta-cyclopiazonate dehydrogenase cpaO then carries out the dehydrogenation of beta-CPA to yield an unstable enimine product, which is captured by intramolecular cyclization to create the pentacyclic fused scaffold of alpha-cyclopiazonate (PubMed:21608094). Fimally, the cytochrome P450 monooxygenase cpaH mediates the conversion of CPA into the less toxic 2-oxocyclopiazonic acid, the end product of the CPA pathway in A.oryza (PubMed:21608094). A + beta-cyclopiazonate = AH2 + alpha-cyclopiazonate Impairs the production of cyclopiazonic acid, but accumulates its biosynthetic intermediates cyclo-acetoacetyl-L-tryptophan and beta-cyclopiazonic acid. Belongs to the beta-cyclopiazonate dehydrogenase family.