title: Reduced peroxisomal citrate synthase activity increases substrate availability for polyhydroxyalkanoate biosynthesis in plant peroxisomes.
abstract: Polyhydroxyalkanoates (PHAs) are bacterial carbon storage polymers used as renewable, biodegradable plastics. PHA production in plants may be a way to reduce industrial PHA production costs. We recently demonstrated a promising level of peroxisomal PHA production in the high biomass crop species sugarcane. However, further production strategies are needed to boost PHA accumulation closer to commercial targets. Through exogenous fatty acid feeding of Arabidopsis thaliana plants that contain peroxisome-targeted PhaA, PhaB and PhaC enzymes from Cupriavidus necator, we show here that the availability of substrates derived from the β-oxidation cycle limits peroxisomal polyhydroxybutyrate (PHB) biosynthesis. Knockdown of peroxisomal citrate synthase activity using artificial microRNA increased PHB production levels approximately threefold. This work demonstrates that reduction of peroxisomal citrate synthase activity may be a valid metabolic engineering strategy for increasing PHA production in other plant species.
authors.affiliation: School of Biological Science, The University of Queensland, Brisbane, Qld, Australia; Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, Qld, Australia; The Cooperative Research Centre for Sugar Industry Innovation through Biotechnology, The University of Queensland, Brisbane, Qld, Australia.
authors.forename: Kimberley
authors.initials: K
authors.lastname: Tilbrook
authors.forename: Yves
authors.initials: Y
authors.lastname: Poirier
authors.forename: Leigh
authors.initials: L
authors.lastname: Gebbie
authors.forename: Peer M
authors.initials: PM
authors.lastname: Schenk
authors.forename: Richard B
authors.initials: RB
authors.lastname: McQualter
authors.forename: Stevens M
authors.initials: SM
authors.lastname: Brumbley
mesh_terms: D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D053898:Biosynthetic Pathways; D002950:Citrate (si)-Synthase / Q000235:genetics* / Q000378:metabolism; D005227:Fatty Acids / Q000378:metabolism; D055785:Gene Knockdown Techniques; D060847:Metabolic Engineering; D010084:Oxidation-Reduction; D020675:Peroxisomes / Q000201:enzymology*; D030821:Plants, Genetically Modified; D054813:Polyhydroxyalkanoates / Q000378:metabolism*; D013379:Substrate Specificity
chemical_list: D029681:Arabidopsis Proteins; D005227:Fatty Acids; D054813:Polyhydroxyalkanoates; D002950:Citrate (si)-Synthase
keywords: Arabidopsis; citrate synthase; peroxisome; plant metabolic engineering; polyhydroxyalkanoate; β-oxidation