PMID- 22827600 OWN - NLM STAT- MEDLINE DCOM- 20130107 LR - 20120817 IS - 1208-6002 (Electronic) IS - 0829-8211 (Linking) VI - 90 IP - 5 DP - 2012 Oct TI - Daphnetin methylation stabilizes the activity of phosphoribulokinase in wheat during cold acclimation. PG - 657-66 LID - 10.1139/o2012-023 [doi] AB - The methylation of daphnetin (7,8-dihydroxycoumarin) to its 8-methyl derivative is catalyzed by a wheat (Triticum aestivum L.) O-methyltransferase (TaOMT1). This enzyme is regulated by cold and photosystem II excitation pressure (plastid redox state). Here, we investigated the biological significance of this methylation and its potential role in modulating the activity of kinases in wheat. To identify the potential kinases that may interact with daphnetin in wheat, the soluble protein extract from aerial parts of cold-acclimated wheat was purified by DEAE-cellulose separation and affinity chromatography on a daphnetin derivative (7,8-dihydroxy-4-coumarin acetic acid)-EAH sepharose column. Mass spectrometric analysis indicated that wheat phosphoribulokinase (TaPRK) is the major kinase that binds to daphnetin. This TaPRK plays an important role in regulating the flow of carbon through the Calvin cycle, by catalyzing the final step in the regeneration of ribulose 1,5-bisphosphate from ribulose-5-phosphate (Ru5P) and ATP. The activities of TaPRK, endogenous or recombinant, are inhibited by daphnetin in a specific and dose-dependent manner, but not by its monomethyl derivative (7-methyl, 8-hydroxycoumarin). Furthermore, HPLC-MS analysis of wheat extracts reveals that 7,8-dimethoxycoumarin is more abundant than its monomethyl derivative. The results also show that cold acclimation does not alter the level of TaPRK mRNA or its enzyme activity, and thus ensures the stable generation of ribulose 1,5-biphosphate. FAU - Kane, Khalil AU - Kane K AD - Departement des Sciences biologiques, Universite du Quebec a Montreal, C.P 8888, Succ. Centre-Ville, Montreal, QC H2X 3X8, Canada. FAU - Moheb, Amira AU - Moheb A FAU - Fukushi, Yukihara AU - Fukushi Y FAU - Roy, Rene AU - Roy R FAU - Huner, Norman P A AU - Huner NP FAU - Ibrahim, Ragai K AU - Ibrahim RK FAU - Sarhan, Fathey AU - Sarhan F LA - eng PT - Journal Article PT - Research Support, Non-U.S. Gov't DEP - 20120725 PL - Canada TA - Biochem Cell Biol JT - Biochemistry and cell biology = Biochimie et biologie cellulaire JID - 8606068 RN - 0 (Coumarins) RN - 0 (RNA, Messenger) RN - 0 (Ribulosephosphates) RN - 0 (Umbelliferones) RN - 2002-28-0 (ribulose-1,5 diphosphate) RN - 2442-31-1 (8-hydroxycoumarin) RN - EC 2.7.1.- (Phosphotransferases (Alcohol Group Acceptor)) RN - EC 2.7.1.19 (phosphoribulokinase) RN - XC84571RD2 (daphnetin) SB - IM MH - Acclimatization MH - *Cold Temperature MH - Coumarins/metabolism/pharmacology MH - Mass Spectrometry MH - Methylation MH - Phosphotransferases (Alcohol Group Acceptor)/genetics/*metabolism MH - RNA, Messenger/metabolism MH - Ribulosephosphates/genetics/metabolism MH - Triticum/*enzymology/metabolism MH - Umbelliferones/metabolism/*pharmacology EDAT- 2012/07/26 06:00 MHDA- 2013/01/08 06:00 CRDT- 2012/07/26 06:00 PHST- 2012/07/26 06:00 [entrez] PHST- 2012/07/26 06:00 [pubmed] PHST- 2013/01/08 06:00 [medline] AID - 10.1139/o2012-023 [doi] PST - ppublish SO - Biochem Cell Biol. 2012 Oct;90(5):657-66. doi: 10.1139/o2012-023. Epub 2012 Jul 25.