@article{LorberthRitteWillmitzeretal.1998, author = {Lorberth, Ruth and Ritte, Gerhard and Willmitzer, Lothar and Kossmann, Jens}, title = {Inhibition of a starch-granule-bound protein leads to modified starch and repression of cold sweetening}, year = {1998}, language = {en} } @article{RitteRosenfeldRohrigetal.1999, author = {Ritte, Gerhard and Rosenfeld, J. and Rohrig, K. and Raschke, Klaus}, title = {Rates of sugar uptake by guard cell protoplasts of Pisum sativum L. related to solute requirement for stomatal opening}, year = {1999}, language = {en} } @article{RitteEckermannHaebeletal.2000, author = {Ritte, Gerhard and Eckermann, Nora and Haebel, Sophie and Lorberth, Ruth and Steup, Martin}, title = {Compartmentation of the starch-related R1 protein in higher plants}, year = {2000}, language = {en} } @article{RitteRuthSteup2000, author = {Ritte, Gerhard and Ruth, Lorberth and Steup, Martin}, title = {Reversible binding of the starch-related R1 protein to the surface of transitory starch granules}, year = {2000}, language = {en} } @article{YuKoflerHaeusleretal.2001, author = {Yu, Tien-Shin and Kofler, Heike and H{\"a}usler, Rainer E. and Hille, Diana and Fl{\"u}gge, Ulf-Ingo and Zeeman, Samuel C. and Smith, Alison M. and Kossmann, Jens and Lloyd, James R. and Ritte, Gerhard and Steup, Martin and Lue, Wei-Ling and Chen, Jychian and Weber, Andreas P. M.}, title = {The Arabidopsis sex1 mutant is defective in the R1 protein, a general regulator of starch degradation in plants, and not in the chloroplast hexose transporter}, issn = {1040-4651}, year = {2001}, language = {en} } @article{RitteLloydEckermannetal.2002, author = {Ritte, Gerhard and Lloyd, James R. and Eckermann, Nora and Rottmann, Antje and Kossmann, Jens and Steup, Martin}, title = {The starch-related R1 protein is an a-glucan, water dikinase}, issn = {0027-8424}, year = {2002}, language = {en} } @article{ReimannRitteSteupetal.2002, author = {Reimann, Rezarta and Ritte, Gerhard and Steup, Martin and Appenroth, Klaus-J.}, title = {Association of a-amylase and the R1 protein with starch granules precedes the initiation of net starch degradation in turions of Spirodela polyrhiza}, issn = {0031-9317}, year = {2002}, language = {en} } @article{RitteRaschke2003, author = {Ritte, Gerhard and Raschke, Klaus}, title = {Metabolite export of isolated guard cell chloroplasts of Vicia faba}, year = {2003}, language = {en} } @article{RitteSteupKossmannetal.2003, author = {Ritte, Gerhard and Steup, Martin and Kossmann, Jens and Lloyd, James R.}, title = {Determination of the starch phosphorylating enzyme activity in plant extracts}, year = {2003}, language = {en} } @article{RitteScharfEckermannetal.2004, author = {Ritte, Gerhard and Scharf, Anke and Eckermann, Nora and Haebel, Sophie and Steup, Martin}, title = {Phosphorylation of transitory starch is increased during degradation}, year = {2004}, abstract = {The starch excess phenotype of Arabidopsis mutants defective in the starch phosphorylating enzyme glucan, water dikinase (EC 2.7.9.4) indicates that phosphorylation of starch is required for its degradation. However, the underlying mechanism has not yet been elucidated. In this study, two in vivo systems have been established that allow the analysis of phosphorylation of transitory starch during both biosynthesis in the light and degradation in darkness. First, a photoautotrophic culture of the unicellular green alga Chlamydomonas reinhardtii was used to monitor the incorporation of exogenously supplied P-32 orthophosphate into starch. Illuminated cells incorporated P-32 into starch with a constant rate during 2 h. By contrast, starch phosphorylation in darkened cells exceeded that in illuminated cells within the first 30 min, but subsequently phosphate incorporation declined. Pulse-chase experiments performed with P-32/P-31 orthophosphate revealed a high turnover of the starch-bound phosphate esters in darkened cells but no detectable turnover in illuminated cells. Secondly, leaf starch granules were isolated from potato (Solanum tuberosum) plants grown under controlled conditions and glucan chains from the outer granule layer were released by isoamylase. Phosphorylated chains were purified and analyzed using high performance anion-exchange chromatography and matrix-assisted laser desorption/ionization mass spectrometry. Glucans released from the surface of starch granules that had been isolated from darkened leaves possessed a considerably higher degree of phosphorylation than those prepared from leaves harvested during the light period. Thus, in the unicellular alga as well as in potato leaves, net starch degradation is accompanied with an increased phosphorylation of starch}, language = {en} } @article{LloydKossmannRitte2005, author = {Lloyd, James R. and Kossmann, Jens and Ritte, Gerhard}, title = {Leaf starch degradation comes out of the shadows}, year = {2005}, abstract = {During the day, plants accumulate starch in their leaves as an energy source for the coming night. Based on recent findings, the prevailing view of how the transitory starch is remobilized needs considerable revision. Analyses of transgenic and mutant plants demonstrate that plastidic glucan phosphorylase is not required for normal starch breakdown and cast doubt on the presumed essential role of alpha-amylase but do show that beta-amylase is important. Repression of the activity of a plastidic beta-amylase, the export of its product (maltose) or further metabolism of maltose by a newly identified transglucosidase impairs starch degradation. Breakdown of particulate starch also depends on the activity of glucan-water dikinase, which phosphorylates glucosyl residues within the polymer}, language = {en} } @article{KoettingPuschTiessenetal.2005, author = {K{\"o}tting, Oliver and Pusch, Kerstin and Tiessen, Axel and Geigenberger, Peter Ludwig and Steup, Martin and Ritte, Gerhard}, title = {Identification of a novel enzyme required for starch metabolism in Arabidopsis leaves : the phosphoglucan, water dikinase}, year = {2005}, abstract = {The phosphorylation of amylopectin by the glucan, water dikinase (GWD; EC 2.7.9.4) is an essential step within starch metabolism. This is indicated by the starch excess phenotype of GWD-deficient plants, such as the sex1-3 mutant of Arabidopsis (Arabidopsis thaliana). To identify starch-related enzymes that rely on glucan-bound phosphate, we studied the binding of proteins extracted from Arabidopsis wild-type leaves to either phosphorylated or nonphosphorylated starch granules. Granules prepared from the sex1-3 mutant were prephosphorylated in vitro using recombinant potato (Solanum tuberosum) GWD. As a control, the unmodified, phosphate free granules were used. An as-yet uncharacterized protein was identified that preferentially binds to the phosphorylated starch. The C-terminal part of this protein exhibits similarity to that of GWD. The novel protein phosphorylates starch granules, but only following prephosphorylation with GWD. The enzyme transfers the beta-P of ATP to the phosphoglucan, whereas the gamma-P is released as orthophosphate. Therefore, the novel protein is designated as phosphoglucan, water dikinase (PWD). Unlike GWD that phosphorylates preferentially the C6 position of the glucose units, PWD phosphorylates predominantly (or exclusively) the C3 position. Western-blot analysis of protoplast and chloroplast fractions from Arabidopsis leaves reveals a plastidic location of PWD. Binding of PWD to starch granules strongly increases during net starch breakdown. Transgenic Arabidopsis plants in which the expression of PWD was reduced by either RNAi or a T-DNA insertion exhibit a starch excess phenotype. Thus, in Arabidopsis leaves starch turnover requires a close collaboration of PWD and GWD}, language = {en} } @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{RitteHeydenreichMahlowetal.2006, author = {Ritte, Gerhard and Heydenreich, Matthias and Mahlow, Sebastian and Haebel, Sophie and Koetting, Oliver and Steup, Martin}, title = {Phosphorylation of C6- and C3-positions of glucosyl residues in starch is catalysed by distinct dikinases}, series = {FEBS letters : the journal for rapid publication of short reports in molecular biosciences}, volume = {580}, journal = {FEBS letters : the journal for rapid publication of short reports in molecular biosciences}, number = {20}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0014-5793}, doi = {10.1016/j.febslet.2006.07.085}, pages = {4872 -- 4876}, year = {2006}, abstract = {Glucan, water dikinase (GWD) and phosphoglucan, water dikinase (PWD) are required for normal starch metabolism. We analysed starch phosphorylation in Arabidopsis wildtype plants and mutants lacking either GWD or PWD using P-31 NMR. Phosphorylation at both C6- and C3-positions of glucose moieties in starch was drastically decreased in GWD-deficient mutants. In starch from PWD-deficient plants C3-bound phosphate was reduced to levels close to the detection limit. The latter result contrasts with previous reports according to which GWD phosphorylates both C6- and C3-positions. In these studies, phosphorylation had been analysed by HPLC of acid-hydrolysed glucans. We now show that maltose-6-phosphate, a product of incomplete starch hydrolysis, co-eluted with glucose-3-phosphate under the chromatographic conditions applied. Re-examination of the specificity of the dikinases using an improved method demonstrates that C6- and C3-phosphorylation is selectively catalysed by GWD and PWD, respectively.}, language = {en} } @article{HaebelHejaziFrohbergetal.2008, author = {Haebel, Sophie and Hejazi, Mahdi and Frohberg, Claus and Heydenreich, Matthias and Ritte, Gerhard}, title = {Mass spectrometric quantification of the relative amounts of C6 and C3 position phosphorylated glucosyl residues in starch}, issn = {0003-2697}, year = {2008}, abstract = {The quantification of phosphate bound to the C6 and C3 positions of glucose residues in starch has received increasing interest since the importance of starch phosphorylation for plant metabolism was discovered. The method described here is based on the observation that the isobaric compounds glucose-6-phosphate (Glc6P) and glucose-3- phosphate (Glc3P) exhibit significantly different fragmentation patterns in negative ion electrospray tandem mass spectrometry (MS/MS). A simple experiment involving collision-induced dissociation (CID) MS2 spectra of the sample and the two reference substances Glc3P and Glc6P permitted the quantification of the relative amounts of the two compounds in monosaccharide mixtures generated by acid hydrolysis of starch. The method was tested on well-characterized potato tuber starch. The results are consistent with those obtained by NMR analysis. In contrast to NMR, however, the presented method is fast and can be performed on less than 1 mg of starch. Starch samples of other origins exhibiting a variety of phosphorylation degrees were analyzed to assess the sensitivity and robustness of the method.}, language = {en} } @article{KoettingSanteliaEdneretal.2009, author = {Koetting, Oliver and Santelia, Diana and Edner, Christoph and Eicke, Simona and Marthaler, Tina and Gentry, Matthew S. and Comparot-Moss, Sylviane and Chen, Jychian and Smith, Alison M. and Steup, Martin and Ritte, Gerhard and Zeeman, Samuel C.}, title = {STARCH-EXCESS4 is a laforin-like phosphoglucan phosphatase required for starch degradation in Arabidopsis thaliana}, issn = {1040-4651}, doi = {10.1105/tpc.108.064360}, year = {2009}, abstract = {Starch is the major storage carbohydrate in plants. It is comprised of glucans that form semicrystalline granules. Glucan phosphorylation is a prerequisite for normal starch breakdown, but phosphoglucan metabolism is not understood. A putative protein phosphatase encoded at the Starch Excess 4 (SEX4) locus of Arabidopsis thaliana was recently shown to be required for normal starch breakdown. Here, we show that SEX4 is a phosphoglucan phosphatase in vivo and define its role within the starch degradation pathway. SEX4 dephosphorylates both the starch granule surface and soluble phosphoglucans in vitro, and sex4 null mutants accumulate phosphorylated intermediates of starch breakdown. These compounds are linear alpha-1,4-glucans esterified with one or two phosphate groups. They are released from starch granules by the glucan hydrolases alpha-amylase and isoamylase. In vitro experiments show that the rate of starch granule degradation is increased upon simultaneous phosphorylation and dephosphorylation of starch. We propose that glucan phosphorylating enzymes and phosphoglucan phosphatases work in synergy with glucan hydrolases to mediate efficient starch catabolism.}, language = {en} } @article{LiFranciscoZhouetal.2009, author = {Li, Jing and Francisco, Perigio and Zhou, Wenxu and Edner, Christoph and Steup, Martin and Ritte, Gerhard and Bond, Charles S. and Smith, Steven M.}, title = {Catalytically-inactive beta-amylase BAM4 required for starch breakdown in Arabidopsis leaves is a starch- binding-protein}, issn = {0003-9861}, doi = {10.1016/j.abb.2009.07.024}, year = {2009}, abstract = {Of the four chloroplast beta-amylase (BAM) proteins identified in Arabidopsis, BAM3 and BAM4 were previously shown to play the major roles in leaf starch breakdown, although BAM4 apparently lacks key active site residues and beta- amylase activity. Here we tested multiple BAM4 proteins with different N-terminal sequences with a range of glucan substrates and assay methods, but detected no alpha-1,4-glucan hydrolase activity. BAM4 did not affect BAM1, BAM2 or BAM3 activity even when added in 10-fold excess, nor the BAM3-catalysed release of maltose from isolated starch granules in the presence of glucan water dikinase. However, BAM4 binds to amylopectin and to amylose-Sepharose whereas BAM2 has very low beta-amylase activity and poor glucan binding. The low activity of BAM2 may be explained by poor glucan binding but absence of BAM4 activity is not. These results suggest that BAM4 facilitates starch breakdown by a mechanism involving direct interaction with starch or other alpha-1,4-glucan.}, language = {en} } @article{ComparotMossKoettingStettleretal.2010, author = {Comparot-Moss, Sylviane and Koetting, Oliver and Stettler, Michaela and Edner, Christoph and Graf, Alexander and Weise, Sean E. and Streb, Sebastian and Lue, Wei-Ling and MacLean, Daniel and Mahlow, Sebastian and Ritte, Gerhard and Steup, Martin and Chen, Jychian and Zeeman, Samuel C. and Smith, Alison M.}, title = {A putative phosphatase, LSF1, is required for normal starch turnover in Arabidopsis leaves}, issn = {0032-0889}, doi = {10.1104/pp.109.148981}, year = {2010}, abstract = {A putative phosphatase, LSF1 (for LIKE SEX4; previously PTPKIS2), is closely related in sequence and structure to STARCH-EXCESS4 (SEX4), an enzyme necessary for the removal of phosphate groups from starch polymers during starch degradation in Arabidopsis (Arabidopsis thaliana) leaves at night. We show that LSF1 is also required for starch degradation: lsf1 mutants, like sex4 mutants, have substantially more starch in their leaves than wild-type plants throughout the diurnal cycle. LSF1 is chloroplastic and is located on the surface of starch granules. lsf1 and sex4 mutants show similar, extensive changes relative to wild-type plants in the expression of sugar-sensitive genes. However, although LSF1 and SEX4 are probably both involved in the early stages of starch degradation, we show that LSF1 neither catalyzes the same reaction as SEX4 nor mediates a sequential step in the pathway. Evidence includes the contents and metabolism of phosphorylated glucans in the single mutants. The sex4 mutant accumulates soluble phospho- oligosaccharides undetectable in wild-type plants and is deficient in a starch granule-dephosphorylating activity present in wild-type plants. The lsf1 mutant displays neither of these phenotypes. The phenotype of the lsf1/sex4 double mutant also differs from that of both single mutants in several respects. We discuss the possible role of the LSF1 protein in starch degradation.}, language = {en} }