title: Thioredoxin-mediated reductive activation of a protein kinase for the regulatory phosphorylation of C4-form phosphoenolpyruvate carboxylase from maize.
abstract: The activity of phosphoenolpyruvate carboxylase (PEPC, EC4.1.1.31) for the C4 photosynthesis is known to be regulated mainly in response to light/dark transitions through reversible phosphorylation by a specific protein kinase (PK). PEPC-PK with an M(r) of 30 kDa was purified about 1.4 million-fold to homogeneity from maize leaves and characterized. The purified PEPC-PK was readily inactivated under mild oxidative conditions, but the activity could be recovered by dithiothreitol (DTT). The recovery by DTT was strongly accelerated by thioredoxin (Trx) from E. coli. Trxs of plant origin such as Trx-m from spinach chloroplast and Trx-h from rice cytoplasm were also effective. These results suggest the possibility of PEPC-PK being redox-regulated via Trx in vivo.
authors.affiliation: Division of Applied Biosciences, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto, 606-8502 Japan.
authors.forename: H
authors.initials: H
authors.lastname: Saze
authors.forename: Y
authors.initials: Y
authors.lastname: Ueno
authors.forename: T
authors.initials: T
authors.lastname: Hisabori
authors.forename: H
authors.initials: H
authors.lastname: Hayashi
authors.forename: K
authors.initials: K
authors.lastname: Izui
mesh_terms: D002245:Carbon Dioxide / Q000378:metabolism; D004229:Dithiothreitol / Q000494:pharmacology; D004926:Escherichia coli / Q000737:chemistry; D015971:Gene Expression Regulation, Enzymologic; D008027:Light; D010084:Oxidation-Reduction; D010730:Phosphoenolpyruvate Carboxylase / Q000187:drug effects / Q000378:metabolism*; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational; D017346:Protein Serine-Threonine Kinases / Q000302:isolation & purification / Q000378:metabolism*; D015398:Signal Transduction; D013879:Thioredoxins / Q000378:metabolism* / Q000494:pharmacology; D003313:Zea mays / Q000201:enzymology*
chemical_list: D002245:Carbon Dioxide; D013879:Thioredoxins; C069767:phosphoenolpyruvate carboxylase kinase; D017346:Protein Serine-Threonine Kinases; D010730:Phosphoenolpyruvate Carboxylase; D004229:Dithiothreitol