Fructose 2,6-bisphosphate: a regulator of carbon processing in leaves

Cséke, Csaba; Balogh, Árpád; Wong, Joshua; Buchanan, Bob B.; Stitt, Mark; Herzog, B.; Heldt, Hans W.

doi:10.1016/0968-0004(84)90284-6

Cited by 63 publications

(50 citation statements)

References 21 publications

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“…Sucrose and sucrose phosphate can inhibit the activity of sucrose phosphate synthetase (Salerno & Pontis, 1978;Amir & Preiss, 1982). Such inhibition of carbon utilization in the cytoplasm would result in elevated concentration of chloroplast metabolites and stimulation of chloroplast starch synthesis (Preiss, 1984;Cseke et al, 1984).…”

Section: E § I §mentioning

confidence: 99%

“…Specific fructose 2,6-bis-phosphate Uinase: activated by P, I'OP; mbib.ted by tr,ose-l 5. Specific fructose 2,6-bis-phosphate phosphatase: inhibited by I 1, 1-61 inhibited by the effector molecule fructose 2,6-bis-phosphate (F2,6BP), the synthesis and degradation of which is sensitive to the concentrations of a number of cytoplasmic metabolites (Cseke et al, 1984;Stitt, 1985). Low photosynthetic activity is associated with low rates of carbon export from the chloroplast.…”

Section: E § I §mentioning

confidence: 99%

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Tansley Review No. 5 Fructans and the Metabolism of Sucrose in Vascular Plants

1986

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SUMMARY The occurrence, structure and metabolism of fructose polymers in tissues of vascular plants are discussed in relation to the metabolism of sucrose. Distinctions are made between long‐term and short‐term storage of such polymers and the regulatory mechanisms which govern accumulation are examined. The roles of various fructosyltransferases in the synthesis of the different fructan structures from sucrose are outlined. The potential selective advantages of the possession of fructan metabolism in different species are assessed with reference to possible roles as cryoprotectants, in osmotic control and as storage carbohydrates whose metabolism can continue at low temperatures (0 to 5°C). It is concluded that the complexity and variety of fructan structures and of the associated enzyme systems has resulted in an incomplete understanding of their physiology and biochemistry, but their significance as an alternative storage polysaccharide in both leaves and storage organs should not be underestimated.

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Section: E § I §mentioning

confidence: 99%

Section: E § I §mentioning

confidence: 99%

Tansley Review No. 5 Fructans and the Metabolism of Sucrose in Vascular Plants

1986

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“…We therefore prepared cell-free extracts from each of these two cell types and assayed them for Fru-6-P,2K and Fru-2,6-P2ase activities. Fru-6-P,2K and Fru-2,6-P2ase activities were found mainly in mesophyll cells (Table III (2)(3)(4). Thus, Pi was a strong activator of Fru-6-P,2K and an inhibitor of Fru-2,6-P2ase.…”

Section: Resultsmentioning

confidence: 99%

“…whether sucrose, the most important plant sugar, is synthesized or broken down (2,5, 14). Our laboratory has recently described an enzyme preparation that catalyzes both the synthesis via Fru-6-P,2K (Eq.…”

Section: Introductionmentioning

confidence: 99%

“…Fru-2,6-P2ase Fru-2,6-P2 + H20 -Fru-6-P + Pi (2) Unlike C3 plants, leaves of C4 plants have two types of photosynthetic (parenchyma) cells-mesophyll and bundle sheathin which there is a division of biochemical labor (8,9). Despite comprehensive investigations on chloroplast enzymes, relatively little is known about the production and utilization of sucrose in C4 plants (17) and even less is known about the role of Fru-2,6-P2 in these species.…”

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Enzyme Regulation in C₄ Photosynthesis

Soll

Wötzel²,

Buchanan³

1985

Plant Physiol.

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Activities catalyzing the synthesis of fructose-2,6-bisphosphate (fructose-6-phosphate,2-kinase or Fru-6-P,2K) and its breakdown (fructose-2,6-bisphosphatase or Fru-2,6-P2ase) were identified in leaves of corn (Zea mays), a C4 plant. Fru-6-P,2K and Fru-2,6-P2ase were both localized mainly, if not entirely, in the leaf mesophyll cells. A partially purified preparation containing the two activities revealed that the kinase and phosphatase were regulated by metabolite effectors in a manner generally similar to their counterparts in C3 species. Thus, corn Fru-6-P,2K was activated by inorganic phosphate (Pi) and fructose-6-phosphate, and was inhibited by 3-phosphoglycerate and dihydroxyacetone phosphate. Fru-2,6-P2ase was inhibited by its products, fructose-6-phosphate and Pi. However, unlike its spinach equivalent, corn Fru-2,6-P2ase was also inhibited by 3-phosphoglycerate and, less effectively, by dihydroxyacetone phosphate. The C4 Fru-6-P,2K and Fru-2,6-P2ase were also quite sensitive to inhibition by phosphoenolpyruvate, and each enzyme was also selectively inhibited by certain other metabolites.Fructose-2,6-bisphosphate (Fru-2,6-P2)4 is a regulatory metabolite that functions in determining the route of cytosolic carbon processing in plant cells-i.e. whether sucrose, the most important plant sugar, is synthesized or broken down (2,5, 14). Our laboratory has recently described an enzyme preparation that catalyzes both the synthesis via Fru-6-P,2K (Eq. 1) and the breakdown via Fru-2,6-P2ase (Eq. 2) of Fru-2,6-P2 in leaves of spinach, a C3 plant (3,4,12 4Abbreviations: Fru-2,6-P2, fructose-2,6-bisphosphate; Fru-6-P, fructose-6-phosphate; PGA, 3-phosphoglycerate; DHAP, dihydroxyacetone phosphate; Fru-6-P,2K, fructose-6-phosphate,2-kinase; Fru-2,6-P2ase, fructose-2,6-bisphosphatase; PFP, pyrophosphate-o-fructose-6-phosphate-l-phosphotransferase; PMSF, phenymethylsulfonyl fluoride; Io.s, concentration of inhibitor giving 50% inhibition; Sos, concentration of substrate supporting half-maximal velocity. metabolites in a manner consistent with a role of chloroplasts in determining the fate of cytosolic carbohydrate flux in leaf cells.Fru-6-P + ATP Fru-6-P,2K Fru-2,6-P2 + ADP (1) Fru-2,6-P2ase Fru-2,6-P2 + H20 -Fru-6-P + Pi (2) Unlike C3 plants, leaves of C4 plants have two types of photosynthetic (parenchyma) cells-mesophyll and bundle sheathin which there is a division of biochemical labor (8, 9). Despite comprehensive investigations on chloroplast enzymes, relatively little is known about the production and utilization of sucrose in C4 plants (17) and even less is known about the role of Fru-2,6-P2 in these species. We have, therefore, undertaken a study to localize the synthesis and breakdown of Fru-2,6-P2 in Zea mays (corn), a classical C4 plant. In this paper, we summarize results showing that Fru-6-P,2K and Fru-2,6-P2ase activities are present in corn leaves. The activities, which were localized in mesophyll cells, were regulated by effector metabolites.

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