Literature summary for 1.5.1.8 extracted from

Arruda, P.; Barreto, P.
Lysine catabolism through the saccharopine pathway enzymes and intermediates involved in plant responses to abiotic and biotic stress (2020), Front. Plant Sci., 11, 587 .

Activating Compound

Activating Compound	Comment	Organism	Structure
additional information	in immature maize endosperm, the enzymatic activity of the LKR domain is activated by Ca2+, Mg2+, high salt, and osmolytes	Zea mays
additional information	in immature rice endosperm, the enzymatic activity of the LKR domain is activated by Ca2+, Mg2+, high salt, and osmolytes	Oryza sativa

Cloned(Commentary)

Cloned (Comment)	Organism
gene LKR/SDH, transcriptomic profiling of Arabidopsis thaliana under biotic and abiotic stresses. In Arabidopsis, a monofunctional SDH probably produced from the same gene encoding the bifunctional enzyme localizes in the mitochondria	Arabidopsis thaliana

Localization

Localization	Comment	Organism	GeneOntology No.	Textmining
cytosol	-	Zea mays	5829	-
cytosol	-	Oryza sativa	5829	-
cytosol	-	Brassica napus	5829	-
cytosol	-	Arabidopsis thaliana	5829	-
mitochondrial matrix	-	Homo sapiens	5759	-
additional information	in contrast to the plant enzyme, the animal LKR/SDH is located in the mitochondria matrix	Oryza sativa	-	-
additional information	in contrast to the plant enzyme, the animal LKR/SDH is located in the mitochondria matrix	Brassica napus	-	-
additional information	in contrast to the plant enzyme, the animal LKR/SDH is located in the mitochondria matrix	Homo sapiens	-	-
additional information	in contrast to the plant enzyme, the animal LKR/SDH is located in the mitochondria matrix. In Arabidopsis, a monofunctional SDH probably produced from the same gene encoding the bifunctional enzyme is located in the mitochondria	Arabidopsis thaliana	-	-
additional information	in contrast to the plant enzyme, the animal LKR/SDH is located in the mitochondria matrix. The bifunctional LKR/SDH, at least in immature maize endosperm, is located in the cytosol, but a monofunctional SDH has been found that targets the mitochondria	Zea mays	-	-

Metals/Ions

Metals/Ions	Comment	Organism
Ca2+	activates the LKR domain activity	Zea mays
Ca2+	activates the LKR domain activity	Oryza sativa
Mg2+	activates the LKR domain activity	Zea mays
Mg2+	activates the LKR domain activity	Oryza sativa

Natural Substrates/ Products (Substrates)

Natural Substrates	Organism	Comment (Nat. Sub.)	Natural Products	Comment (Nat. Pro.)	Rev.
N6-(L-1,3-dicarboxypropyl)-L-lysine + NADP+ + H2O	Zea mays	reaction of the LKR domain	L-lysine + 2-oxoglutarate + NADPH + H+	-	r
N6-(L-1,3-dicarboxypropyl)-L-lysine + NADP+ + H2O	Oryza sativa	reaction of the LKR domain	L-lysine + 2-oxoglutarate + NADPH + H+	-	r
N6-(L-1,3-dicarboxypropyl)-L-lysine + NADP+ + H2O	Brassica napus	reaction of the LKR domain	L-lysine + 2-oxoglutarate + NADPH + H+	-	r
N6-(L-1,3-dicarboxypropyl)-L-lysine + NADP+ + H2O	Arabidopsis thaliana	reaction of the LKR domain	L-lysine + 2-oxoglutarate + NADPH + H+	-	r
N6-(L-1,3-dicarboxypropyl)-L-lysine + NADP+ + H2O	Homo sapiens	reaction of the LKR domain	L-lysine + 2-oxoglutarate + NADPH + H+	-	r

Organism

Organism	UniProt	Comment	Textmining
Arabidopsis thaliana	Q9SMZ4	-	-
Brassica napus	Q9FVF4	-	-
Homo sapiens	Q9UDR5	-	-
Oryza sativa	A0A0K0K9B1	-	-
Zea mays	A0A3L6FCN0	-	-

Posttranslational Modification

Posttranslational Modification	Comment	Organism
phosphoprotein	the LKR domain but not the SDH domain is also activated by phosphorylation in a lysine-dependent manner	Zea mays
phosphoprotein	the LKR domain but not the SDH domain is also activated by phosphorylation in a lysine-dependent manner	Oryza sativa
phosphoprotein	the LKR domain but not the SDH domain is also activated by phosphorylation in a lysine-dependent manner	Brassica napus
phosphoprotein	the LKR domain but not the SDH domain is also activated by phosphorylation in a lysine-dependent manner	Arabidopsis thaliana

Source Tissue

Source Tissue	Comment	Organism	Textmining
endosperm	-	Zea mays	-
endosperm	-	Oryza sativa	-
endosperm	-	Arabidopsis thaliana	-
leaf	-	Brassica napus	-

Substrates and Products (Substrate)

Substrates	Comment Substrates	Organism	Products	Comment (Products)	Rev.
additional information	the bifunctional enzyme lysine-ketoglutarate reductase/saccharopine dehydrogenase (LKR/SDH) comprises a LKR domain, which condenses lysine and 2-oxoglutarate into saccharopine, and the SDH domain, that hydrolyzes saccharopine to form glutamate and alpha-aminoadipate semialdehyde, the latter of which is oxidized to alpha-aminoadipate by aminoadipate semialdehyde dehydrogenase (AASADH)	Zea mays	?	-	-
additional information	the bifunctional enzyme lysine-ketoglutarate reductase/saccharopine dehydrogenase (LKR/SDH) comprises a LKR domain, which condenses lysine and 2-oxoglutarate into saccharopine, and the SDH domain, that hydrolyzes saccharopine to form glutamate and alpha-aminoadipate semialdehyde, the latter of which is oxidized to alpha-aminoadipate by aminoadipate semialdehyde dehydrogenase (AASADH)	Oryza sativa	?	-	-
additional information	the bifunctional enzyme lysine-ketoglutarate reductase/saccharopine dehydrogenase (LKR/SDH) comprises a LKR domain, which condenses lysine and 2-oxoglutarate into saccharopine, and the SDH domain, that hydrolyzes saccharopine to form glutamate and alpha-aminoadipate semialdehyde, the latter of which is oxidized to alpha-aminoadipate by aminoadipate semialdehyde dehydrogenase (AASADH)	Brassica napus	?	-	-
additional information	the bifunctional enzyme lysine-ketoglutarate reductase/saccharopine dehydrogenase (LKR/SDH) comprises a LKR domain, which condenses lysine and 2-oxoglutarate into saccharopine, and the SDH domain, that hydrolyzes saccharopine to form glutamate and alpha-aminoadipate semialdehyde, the latter of which is oxidized to alpha-aminoadipate by aminoadipate semialdehyde dehydrogenase (AASADH)	Arabidopsis thaliana	?	-	-
additional information	the bifunctional enzyme lysine-ketoglutarate reductase/saccharopine dehydrogenase (LKR/SDH) comprises a LKR domain, which condenses lysine and 2-oxoglutarate into saccharopine, and the SDH domain, that hydrolyzes saccharopine to form glutamate and alpha-aminoadipate semialdehyde, the latter of which is oxidized to alpha-aminoadipate by aminoadipate semialdehyde dehydrogenase (AASADH)	Homo sapiens	?	-	-
N6-(L-1,3-dicarboxypropyl)-L-lysine + NADP+ + H2O	reaction of the LKR domain	Zea mays	L-lysine + 2-oxoglutarate + NADPH + H+	-	r
N6-(L-1,3-dicarboxypropyl)-L-lysine + NADP+ + H2O	reaction of the LKR domain	Oryza sativa	L-lysine + 2-oxoglutarate + NADPH + H+	-	r
N6-(L-1,3-dicarboxypropyl)-L-lysine + NADP+ + H2O	reaction of the LKR domain	Brassica napus	L-lysine + 2-oxoglutarate + NADPH + H+	-	r
N6-(L-1,3-dicarboxypropyl)-L-lysine + NADP+ + H2O	reaction of the LKR domain	Arabidopsis thaliana	L-lysine + 2-oxoglutarate + NADPH + H+	-	r
N6-(L-1,3-dicarboxypropyl)-L-lysine + NADP+ + H2O	reaction of the LKR domain	Homo sapiens	L-lysine + 2-oxoglutarate + NADPH + H+	-	r

Subunits

Subunits	Comment	Organism
More	the enzyme domains and activities LKR and SDH belong to a single about 120 kDa bifunctional polypeptide	Homo sapiens
More	the enzyme domains and activities LKR and SDH belong to a single about 120 kDa bifunctional polypeptide. In plants, the LKR and SDH domains of the bifunctional polypeptide are separated from each other by an about 130 amino acid interdomain	Zea mays
More	the enzyme domains and activities LKR and SDH belong to a single about 120 kDa bifunctional polypeptide. In plants, the LKR and SDH domains of the bifunctional polypeptide are separated from each other by an about 130 amino acid interdomain	Oryza sativa
More	the enzyme domains and activities LKR and SDH belong to a single about 120 kDa bifunctional polypeptide. In plants, the LKR and SDH domains of the bifunctional polypeptide are separated from each other by an about 130 amino acid interdomain	Brassica napus
More	the enzyme domains and activities LKR and SDH belong to a single about 120 kDa bifunctional polypeptide. In plants, the LKR and SDH domains of the bifunctional polypeptide are separated from each other by an about 130 amino acid interdomain	Arabidopsis thaliana

Synonyms

Synonyms	Comment	Organism
AasS	-	Homo sapiens
LKR	-	Zea mays
LKR	-	Oryza sativa
LKR	-	Brassica napus
LKR	-	Arabidopsis thaliana
LKR	-	Homo sapiens
LKR/SDH	-	Zea mays
LKR/SDH	-	Oryza sativa
LKR/SDH	-	Brassica napus
LKR/SDH	-	Arabidopsis thaliana
LKR/SDH	-	Homo sapiens
lysine-ketoglutarate reductase	-	Zea mays
lysine-ketoglutarate reductase	-	Oryza sativa
lysine-ketoglutarate reductase	-	Brassica napus
lysine-ketoglutarate reductase	-	Arabidopsis thaliana
lysine-ketoglutarate reductase	-	Homo sapiens
lysine-ketoglutarate reductase/saccharopine dehydrogenase	-	Zea mays
lysine-ketoglutarate reductase/saccharopine dehydrogenase	-	Oryza sativa
lysine-ketoglutarate reductase/saccharopine dehydrogenase	-	Brassica napus
lysine-ketoglutarate reductase/saccharopine dehydrogenase	-	Arabidopsis thaliana
lysine-ketoglutarate reductase/saccharopine dehydrogenase	-	Homo sapiens

Cofactor

Cofactor	Comment	Organism
additional information	the LKR domain uses NADP(H) as a cofactor	Zea mays
additional information	the LKR domain uses NADP(H) as a cofactor	Oryza sativa
additional information	the LKR domain uses NADP(H) as a cofactor	Brassica napus
additional information	the LKR domain uses NADP(H) as a cofactor	Arabidopsis thaliana
additional information	the LKR domain uses NADP(H) as a cofactor	Homo sapiens
NADP+	-	Zea mays
NADP+	-	Oryza sativa
NADP+	-	Brassica napus
NADP+	-	Arabidopsis thaliana
NADP+	-	Homo sapiens
NADPH	-	Zea mays
NADPH	-	Oryza sativa
NADPH	-	Brassica napus
NADPH	-	Arabidopsis thaliana
NADPH	-	Homo sapiens

Expression

Organism	Comment	Expression
Zea mays	the enzymes LKR/SDH and AASADH are co-upregulated at the transcriptional level by exogenously applied lysine in plants, animals, and bacteria	up
Oryza sativa	the enzymes LKR/SDH and AASADH are co-upregulated at the transcriptional level by exogenously applied lysine in plants, animals, and bacteria	up
Arabidopsis thaliana	the enzymes LKR/SDH and AASADH are co-upregulated at the transcriptional level by exogenously applied lysine in plants, animals, and bacteria	up
Homo sapiens	the enzymes LKR/SDH and AASADH are co-upregulated at the transcriptional level by exogenously applied lysine in plants, animals, and bacteria	up
Brassica napus	the enzymes LKR/SDH and AASADH are co-upregulated at the transcriptional level by exogenously applied lysine in plants, animals, and bacteria. Hyperosmotic treatment of rapeseed leaf disks induces an increase in LKR/SDH transcript abundance and enzymatic activity, which correlates with decreased levels of free lysine and increased levels of pipecolate. The LKR/SDH activity and pipecolate concentration decrease with the return of the leaf disks to hypoosmotic conditions	up

General Information

General Information	Comment	Organism
evolution	the enzyme domains and activities LKR and SDH belong to a single about 120 kDa bifunctional polypeptide	Homo sapiens
evolution	the enzyme domains and activities LKR and SDH belong to a single about 120 kDa bifunctional polypeptide. In most plants, the enzyme is encoded by a single gene	Zea mays
evolution	the enzyme domains and activities LKR and SDH belong to a single about 120 kDa bifunctional polypeptide. In most plants, the enzyme is encoded by a single gene	Oryza sativa
evolution	the enzyme domains and activities LKR and SDH belong to a single about 120 kDa bifunctional polypeptide. In most plants, the enzyme is encoded by a single gene	Brassica napus
evolution	the enzyme domains and activities LKR and SDH belong to a single about 120 kDa bifunctional polypeptide. In most plants, the enzyme is encoded by a single gene	Arabidopsis thaliana
malfunction	immature endosperms of high-lysine maize mutants, in addition to the bifunctional LKR/SDH polypeptide, also present a small proportion of an active monofunctional SDH	Zea mays
malfunction	immature endosperms of high-lysine maize mutants, in addition to the bifunctional LKR/SDH polypeptide, also present a small proportion of an active monofunctional SDH	Oryza sativa
metabolism	the central enzymes of the saccharopine pathway (SACPATH) catalyze a transamination-like reaction involving the enzymes lysine-ketoglutarate reductase/saccharopine dehydrogenase (LKR/SDH) and the enzyme alpha-aminoadipate semialdehyde dehydrogenase (AASADH). SACPATH involves the conversion of lysine into alpha-aminoadipate by three enzymatic reactions catalyzed by the bifunctional enzyme LKR/SDH and AASADH. The LKR domain condenses lysine and alpha-ketoglutarate into saccharopine, and the SDH domain hydrolyzes saccharopine to form glutamate and alpha-aminoadipate semialdehyde, the latter of which is oxidized to alpha-aminoadipate by AASADH. The LKR domain condenses L-lysine and 2-oxoglutarate into saccharopine using NADPH as a cofactor	Homo sapiens
metabolism	the central enzymes of the saccharopine pathway (SACPATH) catalyze a transamination-like reaction involving the enzymes lysine-ketoglutarate reductase/saccharopine dehydrogenase (LKR/SDH) and the enzyme alpha-aminoadipate semialdehyde dehydrogenase (AASADH). SACPATH involves the conversion of lysine into alpha-aminoadipate by three enzymatic reactions catalyzed by the bifunctional enzyme LKR/SDH and AASADH. The LKR domain condenses lysine and alpha-ketoglutarate into saccharopine, and the SDH domain hydrolyzes saccharopine to form glutamate and alpha-aminoadipate semialdehyde, the latter of which is oxidized to alpha-aminoadipate by AASADH. The LKR domain condenses L-lysine and 2-oxoglutarate into saccharopine using NADPH as a cofactor. Stress-induced protein hydrolysis results in increased free lysine levels. Increased lysine pool can also result from the induction of the aspartate (AK) pathway for lysine biosynthesis	Zea mays
metabolism	the central enzymes of the saccharopine pathway (SACPATH) catalyze a transamination-like reaction involving the enzymes lysine-ketoglutarate reductase/saccharopine dehydrogenase (LKR/SDH) and the enzyme alpha-aminoadipate semialdehyde dehydrogenase (AASADH). SACPATH involves the conversion of lysine into alpha-aminoadipate by three enzymatic reactions catalyzed by the bifunctional enzyme LKR/SDH and AASADH. The LKR domain condenses lysine and alpha-ketoglutarate into saccharopine, and the SDH domain hydrolyzes saccharopine to form glutamate and alpha-aminoadipate semialdehyde, the latter of which is oxidized to alpha-aminoadipate by AASADH. The LKR domain condenses L-lysine and 2-oxoglutarate into saccharopine using NADPH as a cofactor. Stress-induced protein hydrolysis results in increased free lysine levels. Increased lysine pool can also result from the induction of the aspartate (AK) pathway for lysine biosynthesis	Oryza sativa
metabolism	the central enzymes of the saccharopine pathway (SACPATH) catalyze a transamination-like reaction involving the enzymes lysine-ketoglutarate reductase/saccharopine dehydrogenase (LKR/SDH) and the enzyme alpha-aminoadipate semialdehyde dehydrogenase (AASADH). SACPATH involves the conversion of lysine into alpha-aminoadipate by three enzymatic reactions catalyzed by the bifunctional enzyme LKR/SDH and AASADH. The LKR domain condenses lysine and alpha-ketoglutarate into saccharopine, and the SDH domain hydrolyzes saccharopine to form glutamate and alpha-aminoadipate semialdehyde, the latter of which is oxidized to alpha-aminoadipate by AASADH. The LKR domain condenses L-lysine and 2-oxoglutarate into saccharopine using NADPH as a cofactor. Stress-induced protein hydrolysis results in increased free lysine levels. Increased lysine pool can also result from the induction of the aspartate (AK) pathway for lysine biosynthesis	Brassica napus
metabolism	the central enzymes of the saccharopine pathway (SACPATH) catalyze a transamination-like reaction involving the enzymes lysine-ketoglutarate reductase/saccharopine dehydrogenase (LKR/SDH) and the enzyme alpha-aminoadipate semialdehyde dehydrogenase (AASADH). SACPATH involves the conversion of lysine into alpha-aminoadipate by three enzymatic reactions catalyzed by the bifunctional enzyme LKR/SDH and AASADH. The LKR domain condenses lysine and alpha-ketoglutarate into saccharopine, and the SDH domain hydrolyzes saccharopine to form glutamate and alpha-aminoadipate semialdehyde, the latter of which is oxidized to alpha-aminoadipate by AASADH. The LKR domain condenses L-lysine and 2-oxoglutarate into saccharopine using NADPH as a cofactor. Stress-induced protein hydrolysis results in increased free lysine levels. Increased lysine pool can also result from the induction of the aspartate (AK) pathway for lysine biosynthesis	Arabidopsis thaliana
physiological function	involvement of the SACPATH pathway in plant responses to abiotic and biotic stresses, overview. The induction of LKR activity by phosphorylation in a lysine-dependent manner implies that this enzyme is quickly activated to produce saccharopine once lysine levels start rising. The immediate increase in LKR activity stimulates increases in SDH activity, as the two activities occur within the same polypeptide. The immediate consequence of these two reaction steps is the increase in the concentration of alpha-aminoadipate semialdehyde, which would require an increase in AASADH and perhaps P5CR activities to maintain alpha-aminoadipate semialdehyde concentrations below toxic levels	Zea mays
physiological function	involvement of the SACPATH pathway in plant responses to abiotic and biotic stresses, overview. The induction of LKR activity by phosphorylation in a lysine-dependent manner implies that this enzyme is quickly activated to produce saccharopine once lysine levels start rising. The immediate increase in LKR activity stimulates increases in SDH activity, as the two activities occur within the same polypeptide. The immediate consequence of these two reaction steps is the increase in the concentration of alpha-aminoadipate semialdehyde, which would require an increase in AASADH and perhaps P5CR activities to maintain alpha-aminoadipate semialdehyde concentrations below toxic levels	Oryza sativa
physiological function	involvement of the SACPATH pathway in plant responses to abiotic and biotic stresses, overview. The induction of LKR activity by phosphorylation in a lysine-dependent manner implies that this enzyme is quickly activated to produce saccharopine once lysine levels start rising. The immediate increase in LKR activity stimulates increases in SDH activity, as the two activities occur within the same polypeptide. The immediate consequence of these two reaction steps is the increase in the concentration of alpha-aminoadipate semialdehyde, which would require an increase in AASADH and perhaps P5CR activities to maintain alpha-aminoadipate semialdehyde concentrations below toxic levels	Brassica napus
physiological function	involvement of the SACPATH pathway in plant responses to abiotic and biotic stresses, overview. The induction of LKR activity by phosphorylation in a lysine-dependent manner implies that this enzyme is quickly activated to produce saccharopine once lysine levels start rising. The immediate increase in LKR activity stimulates increases in SDH activity, as the two activities occur within the same polypeptide. The immediate consequence of these two reaction steps is the increase in the concentration of alpha-aminoadipate semialdehyde, which would require an increase in AASADH and perhaps P5CR activities to maintain alpha-aminoadipate semialdehyde concentrations below toxic levels	Arabidopsis thaliana