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- Title
In Planta Recapitulation of Isoprene Synthase Evolution from Ocimene Synthases.
- Authors
Mingai Li; Jia Xu; Algarra Alarcon, Alberto; Carlin, Silvia; Barbaro, Enrico; Cappellin, Luca; Velikova, Violeta; Vrhovsek, Urska; Loreto, Francesco; Varotto, Claudio
- Abstract
Isoprene is the most abundant biogenic volatile hydrocarbon compound naturally emitted by plants and plays a major role in atmospheric chemistry. It has beenproposed that isoprene synthases (IspS)may readily evolve fromother terpene synthases, but this hypothesis has not been experimentally investigated. We isolated and functionally validated in Arabidopsis the first isoprene synthase gene, AdoIspS, from a monocotyledonous species (Arundo donax L., Poaceae). Phylogenetic reconstruction indicates that AdoIspS and dicots isoprene synthases most likely originated by parallel evolution from TPS-b monoterpene synthases. Site-directed mutagenesis demonstrated in vivo the functional and evolutionary relevance of the residues considered diagnostic for IspS function. One of these positions was identified by saturating mutagenesis as a major determinant of substrate specificity in AdoIspS able to cause in vivo a dramatic change in total volatile emission from hemi- to monoterpenes and supporting evolution of isoprene synthases from ocimene synthases. The mechanism responsible for IspS neofunctionalization by active site size modulation by a single amino acidmutation demonstratedin this studymight be general, as the very sameamino acidic position is implicated in the parallel evolution of different short-chain terpene synthases from both angiosperms and gymnosperms. Based on these results, we present a model reconciling in a unified conceptual framework the apparently contrasting patterns previously observedfor isoprene synthase evolutioninplants. These results indicate thatparallel evolutionmaybedriven by relatively simple biophysical constraints, and illustrate the intimate molecular evolutionary links between the structural and functional bases of traits with global relevance.
- Publication
Molecular Biology & Evolution, 2017, Vol 34, Issue 10, p2583
- ISSN
0737-4038
- Publication type
Article
- DOI
10.1093/molbev/msx178