@article{OrawetzMalinovaOrzechowskietal.2016,
  author    = {Orawetz, Tom and Malinova, Irina and Orzechowski, Slawomir and Fettke, J{\"o}rg},
  title     = {Reduction of the plastidial phosphorylase in potato (Solanum tuberosum L.) reveals impact on storage starch structure during growth at low temperature},
  series = {Plant physiology and biochemistry : an official journal of the Federation of European Societies of Plant Physiology},
  volume    = {100},
  journal   = {Plant physiology and biochemistry : an official journal of the Federation of European Societies of Plant Physiology},
  publisher = {Elsevier},
  address   = {Paris},
  issn      = {0981-9428},
  doi       = {10.1016/j.plaphy.2016.01.013},
  pages     = {141 -- 149},
  year      = {2016},
  abstract  = {Tubers of potato (Solanum tuberosum L.), one of the most important crops, are a prominent example for an efficient production of storage starch. Nevertheless, the synthesis of this storage starch is not completely understood. The plastidial phosphorylase (Phol; EC 2.4.11) catalyzes the reversible transfer of glucosyl residues from glucose-1-phosphate to the non-reducing end of alpha-glucans with the release of orthophosphate. Thus, the enzyme is in principle able to act during starch synthesis. However, so far under normal growth conditions no alterations in tuber starch metabolism were observed. Based on analyses of other species and also from in vitro experiments with potato tuber slices it was supposed, that Phol has a stronger impact on starch metabolism, when plants grow under low temperature conditions. Therefore, we analyzed the starch content, granule size, as well as the internal structure of starch granules isolated from potato plants grown under low temperatures. Besides wild type, transgenic potato plants with a strong reduction in the Phol activity were analyzed. No significant alterations in starch content and granule size were detected. In contrast, when plants were cultivated at low temperatures the chain length distributions of the starch granules were altered. Thus, the granules contained more short glucan chains. That was not observed in the transgenic plants, revealing that Pho1 in wild type is involved in the formation of the short glucan chains, at least at low temperatures. (C) 2016 Elsevier Masson SAS. All rights reserved.},
  language  = {en}
}
@misc{MahlowOrzechowskiFettke2016,
  author    = {Mahlow, Sebastian and Orzechowski, Slawomir and Fettke, J{\"o}rg},
  title     = {Starch phosphorylation: insights and perspectives},
  series = {Cellular and molecular life sciences},
  volume    = {73},
  journal   = {Cellular and molecular life sciences},
  publisher = {Springer},
  address   = {Basel},
  issn      = {1420-682X},
  doi       = {10.1007/s00018-016-2248-4},
  pages     = {2753 -- 2764},
  year      = {2016},
  abstract  = {During starch metabolism, the phosphorylation of glucosyl residues of starch, to be more precise of amylopectin, is a repeatedly observed process. This phosphorylation is mediated by dikinases, the glucan, water dikinase (GWD) and the phosphoglucan, water dikinase (PWD). The starch-related dikinases utilize ATP as dual phosphate donor transferring the terminal gamma-phosphate group to water and the beta-phosphate group selectively to either C6 position or C3 position of a glucosyl residue within amylopectin. By the collaborative action of both enzymes, the initiation of a transition of alpha-glucans from highly ordered, water-insoluble state to a less order state is realized and thus the initial process of starch degradation. Consequently, mutants lacking either GWD or PWD reveal a starch excess phenotype as well as growth retardation. In this review, we focus on the increased knowledge collected over the last years related to enzymatic properties, the precise definition of the substrates, the physiological implications, and discuss ongoing questions.},
  language  = {en}
}