title: MGDG, PG and SQDG regulate the activity of light-dependent protochlorophyllide oxidoreductase.
abstract: Light-dependent protochlorophyllide oxidoreductase (POR) is a plant enzyme involved in the chlorophyll biosynthesis pathway. POR reduces one of the double bonds of the protochlorophyllide (Pchlide) using NADPH and light. In the present study, we found out that phosphatidylglycerol and sulfoquinovosyl diacylglycerol are allosteric regulators of the nucleotide binding, which increase the affinity towards NADPH a 100-fold. Moreover, we showed for the first time that NADH can, like NADPH, form active complexes with Pchlide and POR, however, at much higher concentrations. Additionally, monogalactosyldiacylglycerol (MGDG) was shown to be the main factor responsible for the red shift of the fluorescence emission maximum of Pchlide:POR:NADPH complexes. Importantly, the emission maximum at 654 nm was obtained only for the reaction mixtures supplemented with MGDG and at least one of the negatively charged plant lipids. Moreover, the site-directed mutagenesis allowed us to identify amino acid residues that may be responsible for lipid binding and Pchlide coordination. Our experiments allowed us to identify six different Pchlide:POR complexes that differ in the fluorescence emission maxima of the pigment. The results presented here reveal the contribution of thylakoid lipids in the regulation of the chlorophyll biosynthesis pathway; however, the molecular mechanisms of this process are to be clarified.
authors.affiliation: Department of Plant Physiology and Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387 Kraków, Poland michal.gabruk@uj.edu.pl.
authors.forename: Michal
authors.initials: M
authors.lastname: Gabruk
authors.affiliation: Department of Plant Physiology and Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387 Kraków, Poland.
authors.forename: Beata
authors.initials: B
authors.lastname: Mysliwa-Kurdziel
authors.affiliation: Department of Plant Physiology and Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387 Kraków, Poland.
authors.forename: Jerzy
authors.initials: J
authors.lastname: Kruk
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D002734:Chlorophyll / Q000096:biosynthesis; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D038983:Galactolipids / Q000737:chemistry / Q000378:metabolism*; D015870:Gene Expression; D007700:Kinetics; D008027:Light; D008958:Models, Molecular; D009154:Mutation; D009243:NAD / Q000737:chemistry / Q000378:metabolism; D009249:NADP / Q000737:chemistry / Q000378:metabolism; D044925:Oxidoreductases Acting on CH-CH Group Donors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D010715:Phosphatidylglycerols / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D000072417:Protein Domains; D017433:Protein Structure, Secondary; D011521:Protochlorophyllide / Q000737:chemistry / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013379:Substrate Specificity
chemical_list: D029681:Arabidopsis Proteins; D038983:Galactolipids; D010715:Phosphatidylglycerols; D011994:Recombinant Proteins; C009909:monogalactosyldiacylglycerol; D009243:NAD; D002734:Chlorophyll; D011521:Protochlorophyllide; D009249:NADP; D044925:Oxidoreductases Acting on CH-CH Group Donors; C023886:protochlorophyllide reductase
keywords: allosteric regulation; chlorophyll; plant lipids; protochlorophyllide oxidoreductase