Structure and catalytic mechanism of a cyclic dipeptide prenyltransferase with broad substrate promiscuity.Schuller, J.M., Zocher, G., Liebhold, M., Xie, X., Stahl, M., Li, S.M., Stehle, T.
(2012) J.Mol.Biol. 422: 87-99
- PubMed: 22683356
- DOI: 10.1016/j.jmb.2012.05.033
- Primary Citation of Related Structures:
- PubMed Abstract:
Fungal indole prenyltransferases (PTs) typically act on specific substrates, and they are able to prenylate their target compounds with remarkably high regio- and stereoselectivity. Similar to several indole PTs characterized to date, the cyclic dipe ...
Fungal indole prenyltransferases (PTs) typically act on specific substrates, and they are able to prenylate their target compounds with remarkably high regio- and stereoselectivity. Similar to several indole PTs characterized to date, the cyclic dipeptide N-prenyltransferase (CdpNPT) is able to prenylate a range of diverse substrates, thus exhibiting an unusually broad substrate promiscuity. To define the structural basis for this promiscuity, we have determined crystal structures of unliganded CdpNPT and of a ternary complex of CdpNPT bound to (S)-benzodiazepinedione and thiolodiphosphate. Analysis of the structures reveals a limited number of specific interactions with (S)-benzodiazepinedione, which projects into a largely hydrophobic surface. This surface can also accommodate other substrates, explaining the ability of the enzyme to prenylate a range of compounds. The location of the bound substrates suggests a likely reaction mechanism for the conversion of (S)-benzodiazepinedione. Structure-guided mutagenesis experiments confirm that, in addition to (S)-benzodiazepinedione, CdpNPT can also act on (R)-benzodiazepinedione and several cyclic dipeptides, albeit with relaxed specificity. Finally, nuclear magnetic resonance spectroscopy demonstrates that CdpNPT is a C-3 reverse PT that catalyzes the formation of C-3β prenylated indolines from diketopiperazines of tryptophan-containing cyclic dipeptides.
Interfakultäres Institut für Biochemie, Universität Tübingen, Hoppe-Seyler-Str. 4, 72076 Tübingen, Germany.