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Arabidopsis MAP-Kinase 3 Phosphorylates UDP-Glucose Dehydrogenase : a Key Enzyme Providing UDP-Sugar for Cell Wall Biosynthesis
AuthorKohlberger, Michael ; Thalhamer, Theresa ; Weiss, Richard ; Tenhaken, Raimund
Published in
Plant Molecular Biology Reporter, New York, 2018, Vol. 36, Issue 5-6, page 870-877
PublishedNew York : Springer US, 2018
Document typeJournal Article
Keywords (EN)Nucleotide sugar biosynthesis / Enzyme regulation / MAPK / UDP-glucose / UDP-glucuronic acid
URNurn:nbn:at:at-ubs:3-10992 Persistent Identifier (URN)
 The work is publicly available
Arabidopsis MAP-Kinase 3 Phosphorylates UDP-Glucose Dehydrogenase [2.44 mb]
Abstract (English)

The enzyme UDP-glucose dehydrogenase (UGD) competes with sucrose-phosphate synthase for the common photosynthesis product UDP-glucose. Sucrose-phosphate synthase is part of a pathway for the export of sucrose from source leaves to neighboring cells or the phloem. UGD is a central enzyme in a pathway for many nucleotide sugars used in local cell wall biosynthesis. Here, we identify a highly conserved phosphorylation site in UGD which is readily phosphorylated by MAP-kinase 3 in Arabidopsis. Phosphorylation occurs at a surface-exposed extra loop in all plant UGDs that is absent in UGDs from bacteria or animals. Phosphorylated sucrose-phosphate synthase is shifted to an inactive form which we did not measure for phosphorylated UGD. Plant UGDs have an extra loop which is phosphorylated by AtMPK3. Phosphorylation is not causing a reduction of UGD activity as found for the competitor enzymes and thus sets a preference for maintaining UDP-sugars at a constant level to prioritize cell wall biosynthesis.

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