Structure of Isoprene Synthase Illuminates the Chemical Mechanism of Teragram Atmospheric Carbon Emission

• Published in: Journal of molecular biology Vol. 402; no. 2; pp. 363 - 373
• Main Authors: Köksal, Mustafa, Zimmer, Ina, Schnitzler, Jörg-Peter, Christianson, David W.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 17.09.2010
• Subjects: 02 PETROLEUM; Alkyl and Aryl Transferases - chemistry; Alkyl and Aryl Transferases - metabolism; BIOSYNTHESIS; Butadienes - metabolism; CARBON; Chimera; Coenzymes - chemistry; Coenzymes - metabolism; CRYSTAL STRUCTURE; CRYSTALLOGRAPHY; Crystallography, X-Ray; Enzyme Inhibitors - chemistry; Enzyme Inhibitors - metabolism; enzyme mechanism; ENZYMES; hemiterpene synthase; Hemiterpenes - chemistry; Hemiterpenes - metabolism; HYDROCARBONS; ISOPRENE; Magnesium - chemistry; Magnesium - metabolism; Models, Molecular; national synchrotron light source; Organophosphorus Compounds - chemistry; Organophosphorus Compounds - metabolism; Pentanes - metabolism; PETROCHEMICALS; POPLARS; Populus - enzymology; Protein Binding; protein crystallography; PROTEIN ENGINEERING; Protein Structure, Tertiary; PROTEINS; RESOLUTION; SUBSTRATES; terpenoid biosynthesis; protein crystallography; GC–MS; LMNS; GPP; hemiterpene synthase; DMAPP; terpenoid biosynthesis; enzyme mechanism; BPPS; DMASPP; ISPS; PDB
• ISSN: 0022-2836; 1089-8638
• DOI: 10.1016/j.jmb.2010.07.009

The X-ray crystal structure of recombinant PcISPS (isoprene synthase from gray poplar hybrid Populus × canescens) has been determined at 2.7 Å resolution, and the structure of its complex with three Mg 2+ and the unreactive substrate analogue dimethylallyl- S-thiolodiphosphate has been determined at 2.8 Å resolution. Analysis of these structures suggests that the generation of isoprene from substrate dimethylallyl diphosphate occurs via a syn-periplanar elimination mechanism in which the diphosphate-leaving group serves as a general base. This chemical mechanism is responsible for the annual atmospheric emission of 100 Tg of isoprene by terrestrial plant life. Importantly, the PcISPS structure promises to guide future protein engineering studies, potentially leading to hydrocarbon fuels and products that do not rely on traditional petrochemical sources.