@article{DauvilleeChochoisSteupetal.2006,
  author    = {Dauvillee, David and Chochois, Vincent and Steup, Martin and Haebel, Sophie and Eckermann, Nora and Ritte, Gerhard and Ral, Jean-Philippe and Colleoni, Christophe and Hicks, Glenn and Wattebled, Fabrice and Deschamps, Philippe and Lienard, Luc and Cournac, Laurent and Putaux, Jean-Luc and Dupeyre, Danielle and Ball, Steven G.},
  title     = {Plastidial phosphorylase is required for normal starch synthesis in Chlamydomonas reinhardtii},
  series = {The plant journal},
  volume    = {48},
  journal   = {The plant journal},
  number    = {2},
  publisher = {Blackwell},
  address   = {Oxford},
  issn      = {0960-7412},
  doi       = {10.1111/j.1365-313X.2006.02870.x},
  pages     = {274 -- 285},
  year      = {2006},
  abstract  = {Among the three distinct starch phosphorylase activities detected in Chlamydomonas reinhardtii, two distinct plastidial enzymes (PhoA and PhoB) are documented while a single extraplastidial form (PhoC) displays a higher affinity for glycogen as in vascular plants. The two plastidial phosphorylases are shown to function as homodimers containing two 91-kDa (PhoA) subunits and two 110-kDa (PhoB) subunits. Both lack the typical 80-amino-acid insertion found in the higher plant plastidial forms. PhoB is exquisitely sensitive to inhibition by ADP-glucose and has a low affinity for malto-oligosaccharides. PhoA is more similar to the higher plant plastidial phosphorylases: it is moderately sensitive to ADP-glucose inhibition and has a high affinity for unbranched malto-oligosaccharides. Molecular analysis establishes that STA4 encodes PhoB. Chlamydomonas reinhardtii strains carrying mutations at the STA4 locus display a significant decrease in amounts of starch during storage that correlates with the accumulation of abnormally shaped granules containing a modified amylopectin structure and a high amylose content. The wild-type phenotype could be rescued by reintroduction of the cloned wild-type genomic DNA, thereby demonstrating the involvement of phosphorylase in storage starch synthesis.},
  language  = {en}
}
@article{FettkeChiaEckermannetal.2006,
  author    = {Fettke, J{\"o}rg and Chia, Tansy and Eckermann, Nora and Smith, Alison M. and Steup, Martin},
  title     = {A transglucosidase necessary for starch degradation and maltose metabolism in leaves at night acts on cytosolic heteroglycans (SHG)},
  issn      = {0960-7412},
  doi       = {10.1111/j.1365-313X.2006.02732.x},
  year      = {2006},
  abstract  = {The recently characterized cytosolic transglucosidase DPE2 (EC 2.4.1.25) is essential for the cytosolic metabolism of maltose, an intermediate on the pathway by which starch is converted to sucrose at night. In in vitro assays, the enzyme utilizes glycogen as a glucosyl acceptor but the in vivo acceptor molecules remained unknown. In this communication we present evidence that DPE2 acts on the recently identified cytosolic water-soluble heteroglycans (SHG) as does the cytosolic phosphorylase (EC 2.4.1.1) isoform. By using in vitro two-step C-14 labeling assays we demonstrate that the two transferases can utilize the same acceptor sites of the SHG. Cytosolic heteroglycans from a DPE2-deficient Arabidopsis mutant were characterized. Compared with the wild type the glucose content of the heteroglycans was increased. Most of the additional glucosyl residues were found in the outer chains of SHG that are released by an endo- alpha-arabinanase (EC 3.2.1.99). Additional starch-related mutants were characterized for further analysis of the increased glucosyl content. Based on these data, the cytosolic metabolism of starch-derived carbohydrates is discussed},
  language  = {en}
}