TY - THES A1 - Malinova, Irina T1 - Analysis of starch metabolism in connection with altered enzyme activities related to central carbon turn-over in Arabidopsis thaliana Y1 - 2012 CY - Potsdam ER - TY - JOUR A1 - Malinova, Irina A1 - Steup, Martin A1 - Fettke, Jörg T1 - Carbon transitions from either Calvin cycle or transitory starch to heteroglycans as revealed by 14-C-labeling experiments using protoplasts from Arabidopsis JF - Physiologia plantarum N2 - Plants metabolize transitory starch by precisely coordinated plastidial and cytosolic processes. The latter appear to include the action of water-soluble heteroglycans (SHG(in)) whose monosaccharide pattern is similar to that of apoplastic glycans (SHG(ex)) but, unlike SHG(ex), SHG(in) strongly interacts with glucosyl transferases. In this study, we analyzed starch metabolism using mesophyll protoplasts from wild-type plants and two knock-out mutants [deficient in the cytosolic transglucosidase, disproportionating isoenzyme 2 (DPE2) or the plastidial phosphoglucomutase (PGM1)] from Arabidopsis thaliana. Protoplasts prelabeled by photosynthetic (CO2)-C-14 fixation were transferred to an unlabeled medium and were darkened or illuminated. Carbon transitions from the Calvin cycle or from starch to both SHG(in) and SHG(ex) were analyzed. In illuminated protoplasts, starch turn-over was undetectable but darkened protoplasts continuously degraded starch. During illumination, neither the total C-14 content nor the labeling patterns of the sugar residues of SHG(in) were significantly altered but both the total amount and the labeling of the constituents of SHG(ex) increased with time. In darkened protoplasts, the C-14-content of most of the sugar residues of SHG(in) transiently and strongly increased and then declined. This effect was not observed in any SHG(ex) constituent. In darkened DPE2-deficient protoplasts, none of the SHG(in) constituents exhibited an essential transient increase in labeling. In contrast, some residues of SHG(in) from the PGM1 mutant exhibited a transient increase in label but this effect significantly differed from that of the wild type. Two conclusions are reached: first, SHG(in) and SHG(ex) exert different metabolic functions and second, SHG(in) is directly involved in starch degradation. Y1 - 2013 U6 - https://doi.org/10.1111/ppl.12033 SN - 0031-9317 VL - 149 IS - 1 SP - 25 EP - 44 PB - Wiley-Blackwell CY - Hoboken ER - TY - JOUR A1 - Fettke, Jörg A1 - Malinova, Irina A1 - Eckermann, Nora A1 - Steup, Martin T1 - Cytosolic heteroglycans in photoautotrophic and in heterotrophic plant cells N2 - In plants several 'starch-related' enzymes exist as plastid- and cytosol-specific isoforms and in some cases the extraplastidial isoforms represent the majority of the enzyme activity. Due to the compartmentation of the plant cells, these extraplastidial isozymes have no access to the plastidial starch granules and, therefore, their in vivo function remained enigmatic. Recently, cytosolic heteroglycans have been identified that possess a complex pattern of the monomer composition and glycosidic bonds. The glycans act both as acceptors and donors for cytosolic glucosyl transferases. In autotrophic tissues the heteroglycans are essential for the nocturnal starch-sucrose conversion. In this review we summarize the current knowledge of these glycans, their interaction with glucosyl transferases and their possible cellular functions. We include data on the heteroglycans in heterotrophic plant tissues and discuss their role in intracellular carbon fluxes that originate from externally supplied carbohydrates. Y1 - 2009 UR - http://www.sciencedirect.com/science/journal/00319422 U6 - https://doi.org/10.1016/j.phytochem.2009.03.016 SN - 0031-9422 ER - TY - JOUR A1 - Malinova, Irina A1 - Mahlow, Sebastian A1 - Alseekh, Saleh A1 - Orawetz, Tom A1 - Fernie, Alisdair R. A1 - Baumann, Otto A1 - Steup, Martin A1 - Fettke, Jörg T1 - Double knockout mutants of arabidopsis grown under normal conditions reveal that the plastidial phosphorylase isozyme participates in transitory starch metabolism JF - Plant physiology : an international journal devoted to physiology, biochemistry, cellular and molecular biology, biophysics and environmental biology of plants N2 - In leaves of two starch-related single-knockout lines lacking either the cytosolic transglucosidase (also designated as disproportionating enzyme 2, DPE2) or the maltose transporter (MEX1), the activity of the plastidial phosphorylase isozyme (PHS1) is increased. In both mutants, metabolism of starch-derived maltose is impaired but inhibition is effective at different subcellular sites. Two constitutive double knockout mutants were generated (designated as dpe2-1 x phs1a and mex1 x phs1b) both lacking functional PHS1. They reveal that in normally grown plants, the plastidial phosphorylase isozyme participates in transitory starch degradation and that the central carbon metabolism is closely integrated into the entire cell biology. All plants were grown either under continuous illumination or in a light-dark regime. Both double mutants were compromised in growth and, compared with the single knockout plants, possess less average leaf starch when grown in a light-dark regime. Starch and chlorophyll contents decline with leaf age. As revealed by transmission electron microscopy, mesophyll cells degrade chloroplasts, but degradation is not observed in plants grown under continuous illumination. The two double mutants possess similar but not identical phenotypes. When grown in a light-dark regime, mesophyll chloroplasts of dpe2-1 x phs1a contain a single starch granule but under continuous illumination more granules per chloroplast are formed. The other double mutant synthesizes more granules under either growth condition. In continuous light, growth of both double mutants is similar to that of the parental single knockout lines. Metabolite profiles and oligoglucan patterns differ largely in the two double mutants. Y1 - 2014 U6 - https://doi.org/10.1104/pp.113.227843 SN - 0032-0889 SN - 1532-2548 VL - 164 IS - 2 SP - 907 EP - 921 PB - American Society of Plant Physiologists CY - Rockville ER - TY - JOUR A1 - Malinova, Irina A1 - Mahto, Harendra A1 - Brandt, Felix A1 - AL-Rawi, Shadha A1 - Qasim, Hadeel A1 - Brust, Henrike A1 - Hejazi, Mahdi A1 - Fettke, Jörg T1 - EARLY STARVATION1 specifically affects the phosphorylation action of starch-related dikinases JF - The plant journal N2 - Starch phosphorylation by starch-related dikinases glucan, water dikinase (GWD) and phosphoglucan, water dikinase (PWD) is a key step in starch degradation. Little information is known about the precise structure of the glucan substrate utilized by the dikinases and about the mechanisms by which these structures may be influenced. A 50-kDa starch-binding protein named EARLY STARVATION1 (ESV1) was analyzed regarding its impact on starch phosphorylation. In various invitro assays, the influences of the recombinant protein ESV1 on the actions of GWD and PWD on the surfaces of native starch granules were analyzed. In addition, we included starches from various sources as well as truncated forms of GWD. ESV1 preferentially binds to highly ordered, -glucans, such as starch and crystalline maltodextrins. Furthermore, ESV1 specifically influences the action of GWD and PWD at the starch granule surface. Starch phosphorylation by GWD is decreased in the presence of ESV1, whereas the action of PWD increases in the presence of ESV1. The unique alterations observed in starch phosphorylation by the two dikinases are discussed in regard to altered glucan structures at the starch granule surface. KW - Arabidopsis thaliana KW - EARLY STARVATION1 KW - glucan KW - phosphoglucan KW - starch granule surface KW - starch phosphorylation KW - water dikinase Y1 - 2018 U6 - https://doi.org/10.1111/tpj.13937 SN - 0960-7412 SN - 1365-313X VL - 95 IS - 1 SP - 126 EP - 137 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Fettke, Jörg A1 - Malinova, Irina A1 - Albrecht, Tanja A1 - Hejazi, Mahdi A1 - Steup, Martin T1 - Glucose-1-Phosphate transport into protoplasts and chloroplasts from leaves of arabidopsis JF - Plant physiology : an international journal devoted to physiology, biochemistry, cellular and molecular biology, biophysics and environmental biology of plants N2 - Almost all glucosyl transfer reactions rely on glucose-1-phosphate (Glc-1-P) that either immediately acts as glucosyl donor or as substrate for the synthesis of the more widely used Glc dinucleotides, ADPglucose or UDPglucose. In this communication, we have analyzed two Glc-1-P-related processes: the carbon flux from externally supplied Glc-1-P to starch by either mesophyll protoplasts or intact chloroplasts from Arabidopsis (Arabidopsis thaliana). When intact protoplasts or chloroplasts are incubated with [U-C-14]Glc-1-P, starch is rapidly labeled. Incorporation into starch is unaffected by the addition of unlabeled Glc-6-P or Glc, indicating a selective flux from Glc-1-P to starch. However, illuminated protoplasts incorporate less C-14 into starch when unlabeled bicarbonate is supplied in addition to the C-14-labeled Glc-1-P. Mesophyll protoplasts incubated with [U-C-14] Glc-1-P incorporate C-14 into the plastidial pool of adenosine diphosphoglucose. Protoplasts prepared from leaves of mutants of Arabidopsis that lack either the plastidial phosphorylase or the phosphoglucomutase isozyme incorporate C-14 derived from external Glc-1-P into starch, but incorporation into starch is insignificant when protoplasts from a mutant possessing a highly reduced ADPglucose pyrophosphorylase activity are studied. Thus, the path of assimilatory starch biosynthesis initiated by extraplastidial Glc-1-P leads to the plastidial pool of adenosine diphosphoglucose, and at this intermediate it is fused with the Calvin cycle-driven route. Mutants lacking the plastidial phosphoglucomutase contain a small yet significant amount of transitory starch. Y1 - 2011 U6 - https://doi.org/10.1104/pp.110.168716 SN - 0032-0889 VL - 155 IS - 4 SP - 1723 EP - 1734 PB - American Society of Plant Physiologists CY - Rockville ER - TY - JOUR A1 - Malinova, Irina A1 - Kössler, Stella A1 - Orawetz, Tom A1 - Matthes, Ulrike A1 - Orzechowski, Slawomir A1 - Koch, Anke A1 - Fettke, Jörg T1 - Identification of two Arabidopsis thaliana plasma membrane transporters able to transport glucose 1-phosphate JF - Plant & cell physiology N2 - Primary carbohydrate metabolism in plants includes several sugar and sugar-derivative transport processes. Over recent years, evidences have shown that in starch-related transport processes, in addition to glucose 6-phosphate, maltose, glucose and triose-phosphates, glucose 1-phosphate also plays a role and thereby increases the possible fluxes of sugar metabolites in planta. In this study, we report the characterization of two highly similar transporters, At1g34020 and At4g09810, in Arabidopsis thaliana, which allow the import of glucose 1-phosphate through the plasma membrane. Both transporters were expressed in yeast and were biochemically analyzed to reveal an antiport of glucose 1-phosphate/phosphate. Furthermore, we showed that the apoplast of Arabidopsis leaves contained glucose 1-phosphate and that the corresponding mutant of these transporters had higher glucose 1-phosphate amounts in the apoplast and alterations in starch and starch-related metabolism. KW - apoplast KW - Arabidopsis thaliana KW - glucose 1-phosphate transport KW - starch metabolism KW - sugar transport Y1 - 2020 U6 - https://doi.org/10.1093/pcp/pcz206 SN - 0032-0781 SN - 1471-9053 VL - 61 IS - 2 SP - 381 EP - 392 PB - Oxford University Press CY - Oxford ER - TY - JOUR A1 - Kunz, Hans-Henning A1 - Zamani-Nour, Shirin A1 - Haeusler, Rainer E. A1 - Ludewig, Katja A1 - Schroeder, Julian I. A1 - Malinova, Irina A1 - Fettke, Jörg A1 - Fluegge, Ulf-Ingo A1 - Gierth, Markus T1 - Loss of cytosolic phosphoglucose isomerase affects carbohydrate metabolism in leaves and is essential for fertility of arabidopsis JF - Plant physiology : an international journal devoted to physiology, biochemistry, cellular and molecular biology, biophysics and environmental biology of plants N2 - Carbohydrate metabolism in plants is tightly linked to photosynthesis and is essential for energy and carbon skeleton supply of the entire organism. Thus, the hexose phosphate pools of the cytosol and the chloroplast represent important metabolic resources that are maintained through action of phosphoglucose isomerase (PGI) and phosphoglucose mutase interconverting glucose 6-phosphate, fructose 6-phosphate, and glucose 1-phosphate. Here, we investigated the impact of disrupted cytosolic PGI (cPGI) function on plant viability and metabolism. Overexpressing an artificial microRNA targeted against cPGI (amiR-cpgi) resulted in adult plants with vegetative tissue essentially free of cPGI activity. These plants displayed diminished growth compared with the wild type and accumulated excess starch in chloroplasts but maintained low sucrose content in leaves at the end of the night. Moreover, amiR-cpgi plants exhibited increased nonphotochemical chlorophyll a quenching during photosynthesis. In contrast to amiR-cpgi plants, viable transfer DNA insertion mutants disrupted in cPGI function could only be identified as heterozygous individuals. However, homozygous transfer DNA insertion mutants could be isolated among plants ectopically expressing cPGI. Intriguingly, these plants were only fertile when expression was driven by the ubiquitin10 promoter but sterile when the seed-specific unknown seed protein promoter or the Cauliflower mosaic virus 35S promoter were employed. These data show that metabolism is apparently able to compensate for missing cPGI activity in adult amiR-cpgi plants and indicate an essential function for cPGI in plant reproduction. Moreover, our data suggest a feedback regulation in amiR-cpgi plants that fine-tunes cytosolic sucrose metabolism with plastidic starch turnover. Y1 - 2014 U6 - https://doi.org/10.1104/pp.114.241091 SN - 0032-0889 SN - 1532-2548 VL - 166 IS - 2 SP - 753 EP - U960 PB - American Society of Plant Physiologists CY - Rockville ER - TY - GEN A1 - Malinova, Irina A1 - Qasim, Hadeel M. A1 - Brust, Henrike A1 - Fettke, Jörg T1 - Parameters of Starch Granule Genesis in Chloroplasts of Arabidopsis thaliana T2 - Frontiers in Plant Science N2 - Starch is the primary storage carbohydrate in most photosynthetic organisms and allows the accumulation of carbon and energy in form of an insoluble and semi-crystalline particle. In the last decades large progress, especially in the model plant Arabidopsis thaliana, was made in understanding the structure and metabolism of starch and its conjunction. The process underlying the initiation of starch granules remains obscure, although this is a fundamental process and seems to be strongly regulated, as in Arabidopsis leaves the starch granule number per chloroplast is fixed with 5-7. Several single, double, and triple mutants were reported in the last years that showed massively alterations in the starch granule number per chloroplast and allowed further insights in this important process. This mini review provides an overview of the current knowledge of processes involved in the initiation and formation of starch granules. We discuss the central role of starch synthase 4 and further proteins for starch genesis and affecting metabolic factors. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 478 KW - starch biosynthesis KW - starch granule biogenesis KW - starch synthase KW - plastidial phosphorylase KW - maltooligosaccharides Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-419295 UR - urn:nbn:de:kobv:517-opus4-419295 ER - TY - JOUR A1 - Malinova, Irina A1 - Qasim, Hadeel M. A1 - Brust, Henrike A1 - Fettke, Jörg T1 - Parameters of Starch Granule Genesis in Chloroplasts of Arabidopsis thaliana JF - Frontiers in Plant Science N2 - Starch is the primary storage carbohydrate in most photosynthetic organisms and allows the accumulation of carbon and energy in form of an insoluble and semi-crystalline particle. In the last decades large progress, especially in the model plant Arabidopsis thaliana, was made in understanding the structure and metabolism of starch and its conjunction. The process underlying the initiation of starch granules remains obscure, although this is a fundamental process and seems to be strongly regulated, as in Arabidopsis leaves the starch granule number per chloroplast is fixed with 5-7. Several single, double, and triple mutants were reported in the last years that showed massively alterations in the starch granule number per chloroplast and allowed further insights in this important process. This mini review provides an overview of the current knowledge of processes involved in the initiation and formation of starch granules. We discuss the central role of starch synthase 4 and further proteins for starch genesis and affecting metabolic factors. KW - starch biosynthesis KW - starch granule biogenesis KW - starch synthase KW - plastidial phosphorylase KW - maltooligosaccharides Y1 - 2018 U6 - https://doi.org/10.3389/fpls.2018.00761 SN - 1664-462X VL - 9 SP - 1 EP - 7 PB - Frontiers Media CY - Lausanne ER -