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Structure of type II terpene cyclase MstE from Scytonema (apo)Structure of type II terpene cyclase MstE from Scytonema (apo)
Structural highlights
FunctionPublication Abstract from PubMedClass II terpene cyclases, such as oxidosqualene and squalene-hopene cyclases, catalyse some of the most complex polycyclization reactions. They minimally exhibit a beta,gamma-didomain architecture that has been evolutionarily repurposed in a wide range of terpene-processing enzymes and likely resulted from a fusion of unidentified monodomain proteins. Although single domain class I terpene cyclases have already been identified, the corresponding class II counterparts have not been previously reported. Here we present high-resolution X-ray structures of a monodomain class II cyclase, merosterolic acid synthase (MstE). With a minimalistic beta-domain architecture, this cyanobacterial enzyme is able to construct four rings in cytotoxic meroterpenoids with a sterol-like topology. The structures with bound substrate, product, and inhibitor provide detailed snapshots of a cyclization mechanism largely governed by residues located in a noncanonical enzyme region. Our results complement the few known class II cyclase crystal structures, while also indicating that archaic monodomain cyclases might have already catalyzed complex reaction cascades. A monodomain class II terpene cyclase assembles complex isoprenoid scaffolds.,Moosmann P, Ecker F, Leopold-Messer S, Cahn JKB, Dieterich CL, Groll M, Piel J Nat Chem. 2020 Aug 10. pii: 10.1038/s41557-020-0515-3. doi:, 10.1038/s41557-020-0515-3. PMID:32778689[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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