Download MendeleyCharacterization of Class IB Terpene Synthase: The First Crystal Structure Bound with a Substrate Surrogate.
Stepanova, R., Inagi, H., Sugawara, K., Asada, K., Nishi, T., Ueda, D., Yasuno, Y., Shinada, T., Miki, K., Fujihashi, M., Sato, T.(2020) ACS Chem Biol 15: 1517-1525
- PubMed: 32227910
- DOI: https://doi.org/10.1021/acschembio.0c00145
- Primary Citation of Related Structures:
6LOO, 6LOP - PubMed Abstract:
Terpene synthases (TS) are classified into two broad types, Class I and II, based on the chemical strategy for initial carbocation formation and motif sequences of the catalytic site. We have recently identified a new class of enzymes, Class IB, showing the acceptability of long (C 20 -C 35 ) prenyl-diphosphates as substrates and no amino acid sequence homology with known TS. Conversion of long prenyl-diphosphates such as heptaprenyl-diphosphate (C 35 ) is unusual and has never been reported for Class I and II enzymes. Therefore, the characterization of Class IB enzymes is crucial to understand the reaction mechanism of the extensive terpene synthesis. Here, we report the crystal structure bound with a substrate surrogate and biochemical analysis of a Class IB TS, using the enzyme from Bacillus alcalophilus (BalTS). The structure analysis revealed that the diphosphate part of the substrate is located around the two characteristic Asp-rich motifs, and the hydrophobic tail is accommodated in a unique hydrophobic long tunnel, where the C 35 prenyl-diphosphate, the longest substrate of BalTS, can be accepted. Biochemical analyses of BalTS showed that the enzymatic property, such as Mg 2+ dependency, is similar to those of Class I enzymes. In addition, a new cyclic terpene was identified from BalTS reaction products. Mutational analysis revealed that five of the six Asp residues in the Asp-rich motifs and two His residues are essential for the formation of the cyclic skeleton. These results provided a clue to consider the application of the unusual large terpene synthesis by Class IB enzymes.
Organizational Affiliation:
Department of Applied Biological Chemistry, Faculty of Agriculture, and Graduate School of Science and Technology, Niigata University, 8050 Ikarashi-2, Niigata 950-2181, Japan.
