Transfer of the cytochrome P450-dependent dhurrin pathway from Sorghum bicolor into Nicotiana tabacum chloroplasts for light-driven synthesis

Thiyagarajan Gnanasekaran, Daniel Karcher, Agnieszka Janina Zygadlo Nielsen, Helle Juel Martens, Stephanie Ruf, Xenia Kroop, Carl Erik Olsen, Mohammed Saddik Motawie, Mathias Pribil, Birger Lindberg Møller, Ralph Bock, Poul Erik Jensen

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Abstract

Plant chloroplasts are light-driven cell factories that have great potential to act as a chassis for metabolic engineering applications. Using plant chloroplasts, we demonstrate how photosynthetic reducing power can drive a metabolic pathway to synthesise a bio-active natural product. For this purpose, we stably engineered the dhurrin pathway from Sorghum bicolor into the chloroplasts of Nicotiana tabacum (tobacco). Dhurrin is a cyanogenic glucoside and its synthesis from the amino acid tyrosine is catalysed by two membrane-bound cytochrome P450 enzymes (CYP79A1 and CYP71E1) and a soluble glucosyltransferase (UGT85B1), and is dependent on electron transfer from a P450 oxidoreductase. The entire pathway was introduced into the chloroplast by integrating CYP79A1, CYP71E1, and UGT85B1 into a neutral site of the N. tabacum chloroplast genome. The two P450s and the UGT85B1 were functional when expressed in the chloroplasts and converted endogenous tyrosine into dhurrin using electrons derived directly from the photosynthetic electron transport chain, without the need for the presence of an NADPH-dependent P450 oxidoreductase. The dhurrin produced in the engineered plants amounted to 0.1-0.2% of leaf dry weight compared to 6% in sorghum. The results obtained pave the way for plant P450s involved in the synthesis of economically important compounds to be engineered into the thylakoid membrane of chloroplasts, and demonstrate that their full catalytic cycle can be driven directly by photosynthesis-derived electrons.

Original languageEnglish
JournalJournal of Experimental Botany
Volume67
Issue number8
Pages (from-to)2495-2506
Number of pages12
ISSN0022-0957
DOIs
Publication statusPublished - 2016

Keywords

  • Journal Article
  • Research Support, Non-U.S. Gov't

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