Metabolic engineering of chloroplasts for artemisinic acid biosynthesis and impact on plant growth.
Chloroplasts offer high-level transgene expression and transgene containment due to maternal inheritance, and are ideal hosts for biopharmaceutical biosynthesis via multigene engineering. To exploit these advantages, we have expressed 12 enzymes in chloroplasts for the biosynthesis of artemisinic acid (precursor of artemisinin, antimalarial drug) in an alternative plant system. Integration of transgenes into the tobacco chloroplast genome via homologous recombination was confirmed by molecular analysis, and biosynthesis of artemisinic acid in plant leaf tissues was detected with the help of 13C NMR and ESI-mass spectrometry. The excess metabolic flux of isopentenyl pyrophosphate generated by an engineered mevalonate pathway was diverted for the biosynthesis of artemisinic acid. However, expression of megatransgenes impacted the growth of the transplastomic plantlets. By combining two exogenous pathways, artemisinic acid was produced in transplastomic plants, which can be improved further using better metabolic engineering strategies for commercially viable yield of desirable isoprenoid products.
International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi 110 067, India.
Bhawna
B
Saxena
Mayavan
M
Subramaniyan
Karan
K
Malhotra
Neel Sarovar
NS
Bhavesh
Shobha Devi
SD
Potlakayala
Shashi
S
Kumar
D037621:Artemisinins; D053898:Biosynthetic Pathways / Q000502:physiology*; D002247:Carbon Isotopes; D002736:Chloroplasts / Q000235:genetics / Q000502:physiology*; D045782:Hemiterpenes / Q000378:metabolism; D059765:Homologous Recombination / Q000235:genetics; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D060847:Metabolic Engineering / Q000379:methods*; D009943:Organophosphorus Compounds / Q000378:metabolism; D014026:Nicotiana / Q000235:genetics* / Q000378:metabolism; D019076:Transgenes / Q000235:genetics
D037621:Artemisinins; D002247:Carbon Isotopes; D045782:Hemiterpenes; D009943:Organophosphorus Compounds; C004809:isopentenyl pyrophosphate; C047721:artemisic acid