Metabolites known to occur in the cytosol of photosynthetic leaf cells were found to mediate the reversible conversion of pyrophosphate—D‐fructose‐6‐phosphate 1‐phosphotransferase (PFP) to phosphofructokinase (PFK) in partially purified preparations from spinach leaves. Preincubation of PFP with fructose 2,6‐bisphosphate, ATP or fructose 6‐phosphate converted PFP to PFK. The reverse reaction (PFK → PFP) was promoted by UDP‐glucose plus pyrophosphate. These conversions in catalytic capability were accompanied by changes in molecular mass and charge. The results are in accord with the view that the alterations in PFP and PFK activity, provisionally called ‘metabolite‐mediated catalyst conversion’, represent a regulatory mechanism to direct left cytosolic carbon flux in either the biosynthetic or degradatory direction.

Fructose 2,6-bisphosphate, a regulatory metabolite discovered in animal cells, plays a central role in regulating carbon metabolism in leaves.

Fructose-2,6-bisphosphate (Fru-2,6-P2) was discovered in mammalian tissues as a powerful activator of liver phosphofructokinase (PFK) and inhibitor of fructose bisphosphatase (Fru-1,6-P2ase) (Hers, Van Schaftingen, 1982; Uyeda et al., 1982). Fru-2,6-P2 is synthesized from F6P and ATP by a specific enzyme fructose-6-phosphate-2-kinase (Fru-6-P,2K) (see Cséke, Buchanan, 1983). The metabolite is hydrolyzed by a phosphatase specific for Fru-2,6-P2: Fructose-2,6-bisphosphatase (Fru-2,6-P2ase) (see Cséke et al., 1983). Cséke et al. (1982) and Stitt et al. (1982) have found that Fru-2,6-P2 is present in green leaves. Recently Cséke and Buchanan (1982) have shown that Fru-6-P,2K is present in the leaves of C3 plants, specifically in the cytoplasm of mesophyll parenchyma cells. The enzyme is regulated by metabolites–inorganic phosphate (Pi), an activator, 3-phosphoglyceric acid (PGA)–an inhibitor. Now we present evidence that an enzyme hydrolyzing Fru-2,6-P2 is also present in spinach extracts and that some of the metabolites modulating Fru-6-P,2K regulate Fru-2,6-P2 in an opposite manner. We also demonstrate that the regulatory properties of the enzymes can account for changes of Fru-2,6-P2 concentration observed in vivo (Stitt et al., this Congress).

Phosphofructokinase of rabbit muscle, which is specific for nucleoside triphosphates such as ATP, dissociated and gained the capability to utilize pyrophosphate as phosphoryl donor following incubation with UDP-glucose. The pyrophosphate- and ATP-linked activities of UDP-glucose-treated muscle phosphofructokinase were promoted by a protein species that showed a molecular weight of 80 kDa (vs. 320 kDa for the untreated enzyme). In the presence of citrate, a known inhibitor of PFK, the pyrophosphate-dependent activity elicited by UDP-glucose treatment was activated by fructose-2,6-bisphosphate. On removal of the UDP-glucose by either dialysis or dilution, the treated enzyme reassociated and became ATP-specific. ATP, dithiothreitol, and fructose-2,6-bisphosphate stimulated reassociation. The results suggest that metabolite-mediated catalyst conversion, yielding an enzyme form capable of utilizing both ATP and pyrophosphate, takes place with the phosphofructokinases of animal tissues.

An enzyme catalyzing the hydrolytic conversion of fructose 2,6‐bisphosphate (Fru‐2,6‐P2) to fructose 6‐phosphate (Fru‐6‐P) and Pi has been identified and purified from plants, specifically the cytosolic fraction of spinach leaf parenchyma cells. Partially purified preparations of the enzyme, designated fructose 2,6‐bisphosphatase (Fru‐2,6‐P2ase), were inhibited by products of the reaction (i.e., Pi and Fru‐6‐P) but showed no response to a protein phosphorylation system known to inhibit the corresponding enzyme in mammalian cells. Fru‐2,6‐P2ase co‐purified with fructose 6‐phosphate,2‐kinase, the enzyme catalyzing the synthesis of Fru‐2,6‐P2. The observed pattern of regulation of the enzymes functional in the synthesis and breakdown of Fru‐2,6‐P2 reinforces the conclusion that chloroplasts play a role in controlling cytosolic carbon processing in leaves.

FEBS LettersVolume 126, Issue 1 p. 85-88 Full-length articleFree Access Redox modulation of glucose-6-P dehydrogenase in Anacystis nidulans and its ‘uncoupling’ by phage infection Csaba Cséke, Csaba Cséke Institute of Plant Physiology, Biological Research Center, Hungarian Academy of Sciences, POB 521, 6701 Szeged, HungarySearch for more papers by this authorÁrpád Balogh, Árpád Balogh Institute of Plant Physiology, Biological Research Center, Hungarian Academy of Sciences, POB 521, 6701 Szeged, HungarySearch for more papers by this authorGábor L. Farkas, Gábor L. Farkas Institute of Plant Physiology, Biological Research Center, Hungarian Academy of Sciences, POB 521, 6701 Szeged, HungarySearch for more papers by this author Csaba Cséke, Csaba Cséke Institute of Plant Physiology, Biological Research Center, Hungarian Academy of Sciences, POB 521, 6701 Szeged, HungarySearch for more papers by this authorÁrpád Balogh, Árpád Balogh Institute of Plant Physiology, Biological Research Center, Hungarian Academy of Sciences, POB 521, 6701 Szeged, HungarySearch for more papers by this authorGábor L. Farkas, Gábor L. Farkas Institute of Plant Physiology, Biological Research Center, Hungarian Academy of Sciences, POB 521, 6701 Szeged, HungarySearch for more papers by this author First published: April 06, 1981 https://doi.org/10.1016/0014-5793(81)81039-3Citations: 29AboutReferencesRelatedInformationPDFPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessClose modalShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL References 1 Á. Balogh, G. Borbély, Cs. Cséke, J. Udvardy, G.L. Farkas, FEBS Lett., 105, (1979), 158– 162. 2 S.S. Cohen, Nature, 168, (1951), 746– 747. 3 H.R. Loeb, S.S. Cohen, J. Biol. Chem., 234, (1959), 364– 369. 4 E.M. Wright, H.Z. Sable, J.L. Bailey, J. Bacteriol., 81, (1961), 845– 851. 5 H.R. Levy, Adv. Enzymol., 48, (1979), 97– 192. 6 R.S. Safferman, T.O. Diener, P.R. Desjardins, M.E. Morris, Virology, 47, (1972), 105– 113. 7 J. Udvardy, B. Sivók, G. Borbély, G.L. Farkas, J. Bacteriol., 126, (1976), 630– 633. 8 G. Borbély, M. Kölcsei, G.L. Farkas, Mol. Biol. Rep., 3, (1976), 139– 142. 9 G. Borbély, Cs. Kari, A. Gulyás, G.L. Farkas, J. Bacteriol., 144, (1980), 859– 864. 10 Cs. Cséke, G.L. Farkas, J. Bacteriol., 137, (1979), 667– 669. 11 J. Biggins, J. Bacteriol., 99, (1969), 570– 575. 12 F. Schaeffer, R.Y. Stanier, Arch. Microbiol., 116, (1978), 9– 19. 13 L.E. Anderson, M. Gibbs E. Latzko Photosynthesis II. Photosynthetic Carbon Metabolism and Related Processes (1979), Springer Berlin, New York 271– 281. 14 B.B. Buchanan, Annu. Rev. Plant. Physiol., 31, (1980), 341– 374. 15 R.A. Wolosiuk, B.B. Buchanan, N.A. Crawford, FEBS Lett., 81, (1977), 253– 258. 16 L. Thelander, P. Reichard, Annu. Rev. Biochem., 48, (1979), 133– 158. 17 J. Glenn, D.H. Duckworth, Arch. Biochem. Biophys., 201, (1980), 576– 585. Citing Literature Volume126, Issue1April 06, 1981Pages 85-88 ReferencesRelatedInformation

FEBS LettersVolume 105, Issue 1 p. 158-162 Full-length articleFree Access Virus infection affects the molecular properties and activity of glucose-6-P dehydrogenase in Anacystis nidulans, a cyanobacterium Novel aspect of metabolic control in a phage-infected cell A. Balogh, A. Balogh Institute of Plant Physiology, Biological Research Center, Hungarian Academy of Sciences, H-6701 Szeged, PO Box 521, HungarySearch for more papers by this authorG. Borbély, G. Borbély Institute of Plant Physiology, Biological Research Center, Hungarian Academy of Sciences, H-6701 Szeged, PO Box 521, HungarySearch for more papers by this authorCs. Cséke, Cs. Cséke Institute of Plant Physiology, Biological Research Center, Hungarian Academy of Sciences, H-6701 Szeged, PO Box 521, HungarySearch for more papers by this authorJ. Udvardy, J. Udvardy Institute of Plant Physiology, Biological Research Center, Hungarian Academy of Sciences, H-6701 Szeged, PO Box 521, HungarySearch for more papers by this authorG.L. Farkas, G.L. Farkas Institute of Plant Physiology, Biological Research Center, Hungarian Academy of Sciences, H-6701 Szeged, PO Box 521, HungarySearch for more papers by this author A. Balogh, A. Balogh Institute of Plant Physiology, Biological Research Center, Hungarian Academy of Sciences, H-6701 Szeged, PO Box 521, HungarySearch for more papers by this authorG. Borbély, G. Borbély Institute of Plant Physiology, Biological Research Center, Hungarian Academy of Sciences, H-6701 Szeged, PO Box 521, HungarySearch for more papers by this authorCs. Cséke, Cs. Cséke Institute of Plant Physiology, Biological Research Center, Hungarian Academy of Sciences, H-6701 Szeged, PO Box 521, HungarySearch for more papers by this authorJ. Udvardy, J. Udvardy Institute of Plant Physiology, Biological Research Center, Hungarian Academy of Sciences, H-6701 Szeged, PO Box 521, HungarySearch for more papers by this authorG.L. Farkas, G.L. Farkas Institute of Plant Physiology, Biological Research Center, Hungarian Academy of Sciences, H-6701 Szeged, PO Box 521, HungarySearch for more papers by this author First published: September 01, 1979 https://doi.org/10.1016/0014-5793(79)80908-4Citations: 17AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL References 1 S.S. Cohen, Fed. Proc. FASEB, 20, (1961), 641– 649. 2 F. Mukai, G. Streisinger, P. Miller, Virology, 33, (1967), 398– 404. 3 A.B. Pardee, R.E. Kunkee, J. Biol. Chem., 199, (1952), 9– 14. 4 E.M. Wright, H.Z. Sable, J.L. Bailey, J. Bacteriol., 81, (1961), 845– 851. 5 R.Y. Stanier, G. Cohen-Bazire, Ann. Rev. Microbiol., 31, (1977), 225– 274. 6 E. Padan, M. Shilo, Bacteriol. Rev., 37, (1973), 343– 370. 7 R.S. Safferman, T.O. Diener, P.R. Desjardins, M.E. Morris, Virology, 47, (1972), 105– 113. 8 J. Udvardy, B. Sivók, G. Borbély, G.L. Farkas, J. Bacteriol., 126, (1976), 630– 633. 9 Cs. Cséke, G.L. Farkas, J. Bacteriol., 137, (1979), 667– 669. 10 G. Borbély, M. Kölcsei, G.L. Farkas, Mol. Biol. Rep., 3, (1976), 139– 142. 11 F. Schaeffer, R.Y. Stanier, Arch. Microbiol., 116, (1978), 9– 19. 12 C. Frieden, J. Biol. Chem., 245, (1970), 5788– 5899. 13 G. Falkner, F. Horner, Plant Physiol., 58, (1976), 717– 718. 14 R.A. Pelroy, R. Rippka, R.Y. Stanier, Arch. Microbiol., 87, (1972), 303– 322. 15 J. Pearce, N.G. Carr, J. Gen. Microbiol., 45, (1969), 451– 462. 16 D.C. Wilson, T. Rees, Plant Physiol., 40, (1965), 332– 335. 17 M.R. Loeb, S.S. Cohen, J. Biol. Chem., 234, (1959), 364– 369. 18 R.A. Pelroy, J.A. Bassham, Arch. Microbiol., 86, (1972), 25– 38. 19 R.A. Pelroy, M.R. Kirk, J.A. Bassham, J. Bacteriol., 128, (1976), 623– 632. 20 P.M. Rubin, E. Zetoony, R.E. McGovan, Plant Physiol., 60, (1977), 407– 411. 21 N.V. Wyen, S. Erdei, G.L. Farkas, Biochim. Biophys. Acta, 232, (1971), 472– 483. Citing Literature Volume105, Issue1September 01, 1979Pages 158-162 ReferencesRelatedInformation