title: Role of isopentenyl-diphosphate isomerase in heterologous cyanobacterial (Synechocystis) isoprene production.
abstract: Heterologous production of isoprene (C5H8) hydrocarbons in cyanobacteria, emanating from sunlight, CO2, and water, is now attracting increasing attention. The concept entails application of an isoprene synthase transgene from terrestrial plants, heterologously expressed in cyanobacteria, aiming to reprogram carbon flux in the terpenoid biosynthetic pathway toward formation and spontaneous release of this volatile chemical from the cell and liquid culture. However, flux manipulations and carbon-partitioning reactions between isoprene (the product) and native terpenoid biosynthesis for cellular needs are not yet optimized for isoprene yield. The primary reactant for isoprene biosynthesis is dimethylallyl diphosphate (DMAPP), whereas both DMAPP and its isopentenyl diphosphate (IPP) isomer are needed for cellular terpenoid biosynthesis. The present work addressed the function of an isopentenyl diphosphate (IPP) isomerase in cyanobacteria and its role in carbon partitioning between IPP and DMAPP, both of which serve, in variable ratios, as reactants for the synthesis of different cellular terpenoids. The work was approached upon the heterologous expression in Synechocystis of the "isopentenyl diphosphate isomerase" gene (FNI) from Streptococcus pneumoniae, using isoprene production as a "reporter process" for substrate partitioning between DMAPP and IPP. It is shown that transgenic expression of the FNI gene in Synechocystis resulted in a 250 % increase in the "reporter isoprene" rate and yield, suggesting that the FNI isomerase shifted the endogenous DMAPP-IPP steady-state pool size toward DMAPP, thereby enhancing rates and yield of isoprene production. The work provides insight into the significance and functional role of the IPP isomerase in these photosynthetic microorganisms.
authors.affiliation: Department of Plant and Microbial Biology, University of California, 111 Koshland Hall, Berkeley, CA, 94720-3102, USA.
authors.forename: Julie E
authors.initials: JE
authors.lastname: Chaves
authors.affiliation: Department of Plant and Microbial Biology, University of California, 111 Koshland Hall, Berkeley, CA, 94720-3102, USA.
authors.forename: Paloma Rueda
authors.initials: PR
authors.lastname: Romero
authors.affiliation: Department of Plant and Microbial Biology, University of California, 111 Koshland Hall, Berkeley, CA, 94720-3102, USA.
authors.forename: Henning
authors.initials: H
authors.lastname: Kirst
authors.affiliation: Department of Plant and Microbial Biology, University of California, 111 Koshland Hall, Berkeley, CA, 94720-3102, USA. melis@berkeley.edu.
authors.forename: Anastasios
authors.identifier: http://orcid.org/0000-0003-2581-4177
authors.initials: A
authors.lastname: Melis
mesh_terms: D002070:Butadienes; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology; D045782:Hemiterpenes / Q000096:biosynthesis* / Q000378:metabolism*; D007535:Isomerases / Q000378:metabolism*; D060847:Metabolic Engineering / Q000379:methods*; D009943:Organophosphorus Compounds / Q000378:metabolism*; D010420:Pentanes; D046939:Synechocystis / Q000201:enzymology* / Q000254:growth & development / Q000378:metabolism; D058615:Synthetic Biology / Q000379:methods
chemical_list: D002070:Butadienes; D045782:Hemiterpenes; D009943:Organophosphorus Compounds; D010420:Pentanes; C005059:isoprene; C004809:isopentenyl pyrophosphate; C043060:3,3-dimethylallyl pyrophosphate; D007535:Isomerases
keywords: Carbon partitioning; Isopentenyl diphosphate isomerase; Isoprene biosynthesis; Metabolic engineering; Synechocystis; Synthetic biology