Mechanism-Based Post-Translational Modification and Inactivation in Terpene Synthases
- Howard Hughes Medical Institute, Jack H. Skirball Center for Chemical Biology & Proteomics, The Salk Institute for Biological Studies, La Jolla, California 92037, United States
- Department of Chemical Physiology, The Scripps Research Institute, La Jolla, California 92037, United States, Vincent J. Coates Mass Spectrometry Center, The Salk Institute of Biological Studies, La Jolla, California 92037, United States
Terpenes are ubiquitous natural chemicals with diverse biological functions spanning all three domains of life. In specialized metabolism, the active sites of terpene synthases (TPSs) evolve in shape and reactivity to direct the biosynthesis of a myriad of chemotypes for organismal fitness. As most terpene biosynthesis mechanistically involves highly reactive carbocationic intermediates, the protein surfaces catalyzing these cascade reactions possess reactive regions possibly prone to premature carbocation capture and potentially enzyme inactivation. Here, we show using proteomic and X-ray crystallographic analyses that cationic intermediates undergo capture by conserved active site residues leading to inhibitory self-alkylation. Furthermore, the level of cation-mediated inactivation increases with mutation of the active site, upon changes in the size and structure of isoprenoid diphosphate substrates, and alongside increases in reaction temperatures. TPSs that individually synthesize multiple products are less prone to self-alkylation then TPSs possessing relatively high product specificity. In total, the results presented suggest that mechanism-based alkylation represents an overlooked mechanistic pressure during the evolution of cation-derived terpene biosynthesis.
- Research Organization:
- Salk Inst. for Biological Studies, La Jolla, CA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES)
- Grant/Contract Number:
- AC02-693-05CH11231; AC02-05CH11231
- OSTI ID:
- 1221692
- Alternate ID(s):
- OSTI ID: 1345035
- Journal Information:
- ACS Chemical Biology, Journal Name: ACS Chemical Biology Vol. 10 Journal Issue: 11; ISSN 1554-8929
- Publisher:
- American Chemical SocietyCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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