TY - JOUR
T1 - Tat proteins as novel thylakoid membrane anchors organize a biosynthetic pathway in chloroplasts and increase product yield 5-fold
AU - Henriques de Jesus, Maria Perestrello Ramos
AU - Nielsen, Agnieszka Janina Zygadlo
AU - Mellor, Silas Busck
AU - Matthes, Annemarie
AU - Burow, Meike
AU - Robinson, Colin
AU - Jensen, Poul Erik
PY - 2017
Y1 - 2017
N2 - Photosynthesis drives the production of ATP and NADPH, and acts as a source of carbon for primary metabolism. NADPH is also used in the production of many natural bioactive compounds. These are usually synthesized in low quantities and are often difficult to produce by chemical synthesis due to their complex structures. Some of the crucial enzymes catalyzing their biosynthesis are the cytochromes P450 (P450s) situated in the endoplasmic reticulum (ER), powered by electron transfers from NADPH. Dhurrin is a cyanogenic glucoside and its biosynthesis involves a dynamic metabolon formed by two P450s, a UDP-glucosyltransferase (UGT) and a P450 oxidoreductase (POR). Its biosynthetic pathway has been relocated to the chloroplast where ferredoxin, reduced through the photosynthetic electron transport chain, serves as an efficient electron donor to the P450s, bypassing the involvement of POR. Nevertheless, translocation of the pathway from the ER to the chloroplast creates other difficulties, such as the loss of metabolon formation and intermediate diversion into other metabolic pathways. We show here that co-localization of these enzymes in the thylakoid membrane leads to a significant increase in product formation, with a concomitant decrease in off-pathway intermediates. This was achieved by exchanging the membrane anchors of the dhurrin pathway enzymes to components of the Twin-arginine translocation pathway, TatB and TatC, which have self-assembly properties. Consequently, we show 5-fold increased titers of dhurrin and a decrease in the amounts of intermediates and side products in Nicotiana benthamiana. Further, results suggest that targeting the UGT to the membrane is a key factor to achieve efficient substrate channeling.
AB - Photosynthesis drives the production of ATP and NADPH, and acts as a source of carbon for primary metabolism. NADPH is also used in the production of many natural bioactive compounds. These are usually synthesized in low quantities and are often difficult to produce by chemical synthesis due to their complex structures. Some of the crucial enzymes catalyzing their biosynthesis are the cytochromes P450 (P450s) situated in the endoplasmic reticulum (ER), powered by electron transfers from NADPH. Dhurrin is a cyanogenic glucoside and its biosynthesis involves a dynamic metabolon formed by two P450s, a UDP-glucosyltransferase (UGT) and a P450 oxidoreductase (POR). Its biosynthetic pathway has been relocated to the chloroplast where ferredoxin, reduced through the photosynthetic electron transport chain, serves as an efficient electron donor to the P450s, bypassing the involvement of POR. Nevertheless, translocation of the pathway from the ER to the chloroplast creates other difficulties, such as the loss of metabolon formation and intermediate diversion into other metabolic pathways. We show here that co-localization of these enzymes in the thylakoid membrane leads to a significant increase in product formation, with a concomitant decrease in off-pathway intermediates. This was achieved by exchanging the membrane anchors of the dhurrin pathway enzymes to components of the Twin-arginine translocation pathway, TatB and TatC, which have self-assembly properties. Consequently, we show 5-fold increased titers of dhurrin and a decrease in the amounts of intermediates and side products in Nicotiana benthamiana. Further, results suggest that targeting the UGT to the membrane is a key factor to achieve efficient substrate channeling.
KW - Chloroplast
KW - Dhurrin
KW - Fusion proteins
KW - Light-driven
KW - Substrate channeling
KW - Twin-arginine translocation pathway
U2 - 10.1016/j.ymben.2017.09.014
DO - 10.1016/j.ymben.2017.09.014
M3 - Journal article
C2 - 28962875
AN - SCOPUS:85030481075
SN - 1096-7176
VL - 44
SP - 108
EP - 116
JO - Metabolic Engineering
JF - Metabolic Engineering
ER -