Malate valves to balance cellular energy supply

DC FieldValueLanguage
dc.contributor.authorScheibe, R
dc.date.accessioned2021-12-23T16:03:00Z-
dc.date.available2021-12-23T16:03:00Z-
dc.date.issued2004
dc.identifier.issn00319317
dc.identifier.urihttps://osnascholar.ub.uni-osnabrueck.de/handle/unios/5738-
dc.description.abstractIn green parts of the plant, during illumination ATP and NAD(P)H act as energy sources that are generated mainly in photosynthesis and respiration, whereas in darkness, glycolysis, respiration and the oxidative pentose-phosphate pathway (OPP) generate the required energy forms. In non-green parts, sugar oxidation in glycolysis, respiration and OPP are the only means of producing energy. For energy-consuming reactions, the delivery of NADPH, NADH, reduced ferredoxin and ATP has to take place at the required rates and in the specific compartments, since the pool sizes of these energy carriers are rather limited and, in general, they are not directly transported across biomembranes. Indirect transport of reducing equivalents can be achieved by malateoxaloacetate shuttles, involving malate dehydrogenase (MDH) for the interconversion. Isoenzymes of MDH are present in each cellular compartment. Chloroplasts contain the redox-controlled NADP-MDH that is only active in the light. In addition, a plastid NAD-MDH that is permanently active and is present in all plastid types has been found. Export of excess NAD(P)H through the malate valves will allow for the continued production of ATP (1) in photosynthesis, and (2) in oxidative phosphorylation. In the latter case, the coupled production of NADH is catalysed by the bispecific NAD(P)-GAPDH (GapAB) in chloroplasts that is active with NAD even in darkness, or by the specific plastid NAD-GAPDH (GapCp) in non-green tissues. When plants are subjected to conditions such as high light, high CO2, NH4+ nutrition, cold stress, which require changed activities of the enzymes of the malate valves, changed expression levels of the MDH isoforms can be observed. In nodules, the induction of a nodule-specific plastid NAD-MDH indicates the changed requirements for energy supply during N-2 fixation. Furthermore, the induction of glucose 6-phosphate dehydrogenase isoforms by ammonium and of ferredoxin and ferredoxin-NADP reductase by nitrate has been described. All these findings are in line with the assumption that a changed redox state caused by metabolic variability leads to the induction of enzymes involved in redox poise.
dc.language.isoen
dc.publisherWILEY
dc.relation.ispartofPHYSIOLOGIA PLANTARUM
dc.subjectCHLOROPLAST ENZYMES
dc.subjectELECTRON-TRANSPORT
dc.subjectESCHERICHIA-COLI
dc.subjectLIGHT ACTIVATION
dc.subjectMETABOLISM
dc.subjectMOLECULAR CHARACTERIZATION
dc.subjectNAD(+)-DEPENDENT GLYCERALDEHYDE-3-PHOSPHATE DEHYDROGENASE
dc.subjectPlant Sciences
dc.subjectROOT PLASTIDS
dc.subjectSTRUCTURAL BASIS
dc.subjectTOBACCO PLANTS
dc.titleMalate valves to balance cellular energy supply
dc.typejournal article
dc.identifier.doi10.1111/j.0031-9317.2004.0222.x
dc.identifier.isiISI:000187890700004
dc.description.volume120
dc.description.issue1
dc.description.startpage21
dc.description.endpage26
dc.identifier.eissn13993054
dc.publisher.place111 RIVER ST, HOBOKEN 07030-5774, NJ USA
dcterms.isPartOf.abbreviationPhysiol. Plant.
crisitem.author.deptFB 05 - Biologie/Chemie-
crisitem.author.deptidfb05-
crisitem.author.orcid0000-0002-6140-6181-
crisitem.author.parentorgUniversität Osnabrück-
crisitem.author.netidScRe288-
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