Purification and Characterization of Bifunctional Lysine-Ketoglutarate Reductase/Saccharopine Dehydrogenase from Developing Soybean Seeds

Miron, Daphna; Ben‐Yaacov, Sari; Reches, Dalit; Schupper, Avigail; Galili, Gad

doi:10.1104/pp.123.2.655

Cited by 24 publications

(13 citation statements)

References 25 publications

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“…LKR condenses lysine and α‐ketoglutarate to form saccharopine, which is subsequently transformed in several steps into acetyl CoA (Galili et al , 2001). Kinetic parameters of Arabidopsis recombinant LKR ( k cat =3.7 s −1 and K m Lys =13 mM) were from Miron et al (2000) (equation S17). THA cleaves Thr into acetaldehyde and Gly, with two isoforms in Arabidopsis that have similar values of K m Thy , in the range 4–7 mM (Joshi et al , 2006).…”

Section: Methodsmentioning

confidence: 99%

Understanding the regulation of aspartate metabolism using a model based on measured kinetic parameters

Curien

Bastien²,

Robert-Genthon

et al. 2009

Molecular Systems Biology

107

121

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The aspartate-derived amino-acid pathway from plants is well suited for analysing the function of the allosteric network of interactions in branched pathways. For this purpose, a detailed kinetic model of the system in the plant model Arabidopsis was constructed on the basis of in vitro kinetic measurements. The data, assembled into a mathematical model, reproduce in vivo measurements and also provide non-intuitive predictions. A crucial result is the identification of allosteric interactions whose function is not to couple demand and supply but to maintain a high independence between fluxes in competing pathways. In addition, the model shows that enzyme isoforms are not functionally redundant, because they contribute unequally to the flux and its regulation. Another result is the identification of the threonine concentration as the most sensitive variable in the system, suggesting a regulatory role for threonine at a higher level of integration.

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Section: Methodsmentioning

confidence: 99%

Understanding the regulation of aspartate metabolism using a model based on measured kinetic parameters

Curien

Bastien²,

Robert-Genthon

et al. 2009

Molecular Systems Biology

107

121

View full text Add to dashboard Cite

show abstract

“…At the same time, there is mounting evidence that substrate channeling is not a common property of bifunctional enzymes catalyzing sequential reactions of a metabolic pathway (3,4,23). These findings suggest that bifunctionality has other potential advantages.…”

Section: Lysine-ketoglutarate Reductase/saccaropine Dehydrogenase Thmentioning

confidence: 80%

“…As discussed above, the functional benefits of a physical linkage between two activities on the same polypeptide have been shown clearly for a number of bifunctional enzymes which catalyze consecutive reactions and exhibit substrate channeling between remote active centers. At the same time, there is mounting evidence that substrate channeling is not a common property of bifunctional enzymes catalyzing sequential reactions of a metabolic pathway (3,4,23). These findings suggest that bifunctionality has other potential advantages.…”

Section: Lysine-ketoglutarate Reductase/saccaropine Dehydrogenase Thmentioning

confidence: 99%

Interdomain Communications in Bifunctional Enzymes: How Are Different Activities Coordinated?

Nagradova

2003

IUBMB Life

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SummaryAlthough bifunctional enzymes containing two different active centers located within separate domains are quite common in living systems, the significance of this bifunctionality is not always clear, and the molecular mechanisms of site-site interactions in such complex systems have come under the scrutiny of science only in recent years. This review summarizes recent data on the mechanisms of communication between active centers in bifunctional enzymes. Three types of enzymes are considered: (1) those catalyzing consecutive reactions of a metabolic pathway and exhibiting substrate channeling (glutamate synthase and imidazole glycerol phosphate synthase), (2) those catalyzing consecutive reactions without substrate channeling (lysine-ketoglutarate reductase/ saccharopine dehydrogenase), and (3) those catalyzing opposed reactions (6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase). The functional role of interdomain communications is briefly discussed.IUBMB Life, 55: 459-466, 2003

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“…1997 ), maize and soybean lack a monofunctional SDH gene product ( Kemper et al . 1999 ; Miron et al . 2000 ).…”

Section: Discussionmentioning

confidence: 99%

A novel composite locus of Arabidopsis encoding two polypeptides with metabolically related but distinct functions in lysine catabolism

et al. 2000

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SummaryBoth plants and animals catabolise lysine via saccharopine by two consecutive enzymes, lysineketoglutarate reductase (LKR) and saccharopine dehydrogenase (SDH), which are linked on a single polypeptide. We recently demonstrated that Arabidopsis plants possess not only a bifunctional LKR/SDH but in addition a monofunctional SDH enzyme. We also speculated that these two enzymes may be controlled by a single gene (G. Tang et al., Plant Cell, 1997. By expressing several epitopetagged and GUS reporter constructs, we demonstrate in the present study that the Arabidopsis monofunctional SDH is encoded by a distinct gene, which is, however, nested entirely within the coding and 3¢ non-coding regions of the larger bifunctional LKR/SDH gene. The entire open reading frame of the monofunctional SDH gene, as well as some components of its promoter, are also parts of the translated coding sequence of the bifunctional LKR/SDH gene. These special structural characteristics, combined with the fact that the two genes encode simultaneously two metabolically related but distinct enzymes, render the LKR/SDH locus a novel type of a composite locus. Not all plant species possess an active monofunctional SDH gene and the production of this enzyme is correlated with an increased¯ux of lysine catabolism. Taken together, our results suggest that the composite LKR/SDH locus serves to control an ef®cient, highly regulated¯ux of lysine catabolism

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Purification and Characterization of Bifunctional Lysine-Ketoglutarate Reductase/Saccharopine Dehydrogenase from Developing Soybean Seeds

Cited by 24 publications

References 25 publications

Understanding the regulation of aspartate metabolism using a model based on measured kinetic parameters

Understanding the regulation of aspartate metabolism using a model based on measured kinetic parameters

Interdomain Communications in Bifunctional Enzymes: How Are Different Activities Coordinated?

A novel composite locus of Arabidopsis encoding two polypeptides with metabolically related but distinct functions in lysine catabolism

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