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Literature summary for 4.2.1.33 extracted from
- Arabidopsis thaliana encodes a bacterial-type heterodimeric isopropylmalate isomerase involved in both Leu biosynthesis and the Met chain elongation pathway of glucosinolate formation (2009), Plant Mol. Biol., 71, 227-239.
Cloned(Commentary)
| Cloned (Comment) | Organism |
|---|---|
| full length reading frame of IPMI small subunit 2 fused in frame to the 5' end of the gene encoding the green fluorescent protein in the vector psmGFP4. Construct transiently expressed in tobacco protoplasts and stably transformed into Arabidopsis plants | Arabidopsis thaliana |
| recombinant expression of GFP-tagged large and small subunit 1 in Arabidopsis thaliana leaves | Arabidopsis thaliana |
Localization
| Localization | Comment | Organism | GeneOntology No. | Textmining |
|---|---|---|---|---|
| chloroplast | - |
Arabidopsis thaliana | 9507 | - |
| chloroplast | presence of different heterodimeric IPMIs in chloroplasts with distinct substrate specificities for Leu or glucosinolate metabolism | Arabidopsis thaliana | 9507 | - |
| chloroplast | presence of different heterodimeric IPMIs in chloroplasts with distinct substrate specificities for Leu or glucosinolate metabolism. Import of the IPMI small subunit 2:GFP fusion protein into chloroplasts | Arabidopsis thaliana | 9507 | - |
Natural Substrates/ Products (Substrates)
| Natural Substrates | Organism | Comment (Nat. Sub.) | Natural Products | Comment (Nat. Pro.) | Rev. | Reac. |
|---|---|---|---|---|---|---|
| (2S)-2-isopropylmalate | Arabidopsis thaliana | - |
(2R,3S)-3-isopropylmalate | - |
? |  |
| (2S)-2-isopropylmalate | Arabidopsis thaliana Col-0 | - |
(2R,3S)-3-isopropylmalate | - |
? | |
Organism
| Organism | UniProt | Comment | Textmining |
|---|---|---|---|
| Arabidopsis thaliana | Q94AR8 | large subunit | - |
| Arabidopsis thaliana | Q94AR8 AND Q9ZW84 | large subunit and small subunit 1 | - |
| Arabidopsis thaliana | Q9LYT7 | small subunit | - |
| Arabidopsis thaliana | Q9ZW84 | small subunit | - |
| Arabidopsis thaliana | Q9ZW85 | small subunit | - |
| Arabidopsis thaliana Col-0 | Q94AR8 AND Q9ZW84 | large subunit and small subunit 1 | - |
Source Tissue
| Source Tissue | Comment | Organism | Textmining |
|---|---|---|---|
| leaf | - |
Arabidopsis thaliana | - |
| rosette leaf | - |
Arabidopsis thaliana | - |
| seed | - |
Arabidopsis thaliana | - |
| seedling | - |
Arabidopsis thaliana | - |
Substrates and Products (Substrate)
| Substrates | Comment Substrates | Organism | Products | Comment (Products) | Rev. | Reac. |
|---|---|---|---|---|---|---|
| (2S)-2-isopropylmalate | - |
Arabidopsis thaliana | (2R,3S)-3-isopropylmalate | - |
? | |
| (2S)-2-isopropylmalate | isomerization via a dehydration and a hydration step | Arabidopsis thaliana | (2R,3S)-3-isopropylmalate | - |
? | |
| (2S)-2-isopropylmalate | - |
Arabidopsis thaliana Col-0 | (2R,3S)-3-isopropylmalate | - |
? | |
| (2S)-2-isopropylmalate | isomerization via a dehydration and a hydration step | Arabidopsis thaliana Col-0 | (2R,3S)-3-isopropylmalate | - |
? | |
| additional information | NMR and mass spectrometric compound determination and analysis, overview | Arabidopsis thaliana | ? | - |
? | |
| additional information | NMR and mass spectrometric compound determination and analysis, overview | Arabidopsis thaliana Col-0 | ? | - |
? | |
Subunits
| Subunits | Comment | Organism |
|---|---|---|
| heterodimer | - |
Arabidopsis thaliana |
Synonyms
| Synonyms | Comment | Organism |
|---|---|---|
| IPMI | - |
Arabidopsis thaliana |
| isopropylmalate dehydratase | - |
Arabidopsis thaliana |
| isopropylmalate isomerase | - |
Arabidopsis thaliana |
Expression
| Organism | Comment | Expression |
|---|---|---|
| Arabidopsis thaliana | in ipmi ssu2-1 plants, absence of mature mRNAs in homozygous plants and the knockout of these genes by T-DNAs | down |
| Arabidopsis thaliana | in ipmi ssu3-1 plants, absence of mature mRNAs in homozygous plants and the knockout of these genes by T-DNAs | down |
| Arabidopsis thaliana | in the ipmilsu1-2mutant mRNA levels are reduced to 65 and 50% of the wild-type standard in seedlings and rosette leaves, respectively, while IPMI large subunit 1 transcript levels are reduced to 40 and 27% of wild-type in these tissues of ipmi lsu1-1 plants. Strongest reduction in ipmi lsu1-3 seedlings (21% of wild-type), while the IPMI large subunit 1 mRNA level in ipmi lsu1-3 reaches about 29% of the wild-type level in leaves | down |
General Information
| General Information | Comment | Organism |
|---|---|---|
| malfunction | for IPMI small subunit 1, no plants homozygous for the T-DNA allele can be obtained in either analyzed line (ipmi ssu1-1 or ipmi ssu1-2) | Arabidopsis thaliana |
| malfunction | homozygous ipmi 3-1mutants can be established. In leaves and seeds of the ipmi ssu3-1 mutant few significant changes in amino acid content. Met levels are unchanged in ipmi ssu3-1 and S-methylmethionine can not be detected | Arabidopsis thaliana |
| malfunction | homozygous ipmi ssu2-1 mutants can be established. Free amino acid content of the leaves and seeds of ipmi ssu2-1 plants is not substantially different from that of the wild-type. S-methylmethionine is not detectable in the ipmi ssu2-1 mutant. Profile of the methionine-derived glucosinolates in leaves of ipmi ssu2-1 does not show substantial variations from that of wild-type plants | Arabidopsis thaliana |
| malfunction | in leaves, ipmi lsu1-2 plants exhibit the weakest chemical phenotype in comparison to wild-type: transport or storage form of Met is barely detectable. Many more changes between the ipmi lsu1-1 and 1-3 plants and wild-type: accumulation of S-methylmethionine in rosette leaves of both mutants which is accompanied by 2fold increased levels of Met. Average 2-isopropylmalate content of 0.42 and 0.02 mg/g dry weight in leaves of ipmi lsu1-3 and ipmi lsu1-1 mutants, respectively, while this metabolite is undetectable in the ipmi lsu1-2 plants. Relative levels of 2-(3'-methylsulfinyl)propylmalate are 10/1/14 in ipmi lsu1-1, 1-2 and 1-3 plants | Arabidopsis thaliana |
| malfunction | isopropylmalate isomerase (IPMI) large subunit mutants reveal accumulation of intermediates of both Leu biosynthesis and Met chain elongation, and an altered composition of aliphatic glucosinolates demonstrating the function of this gene in both pathways In contrast, the small subunits appear to be specialized to either Leu biosynthesis, EC 4.2.1.133, or Met chain elongation, EC 4.2.1.170, metabolic profiling, overview. In large subunit single gene knockout mutant IPMI, the remaining IPMI LSU1 transcript is sufficient for some biosynthesis of Met-derived aliphatic glucosinolates and maintaining Leu levels comparable to wild-type plants | Arabidopsis thaliana |
| metabolism | the enzyme is involved in the leucine biosynthesis. The formation of leucine requires a three-step chain elongation, including a condensation of a 2-oxo acid with acetyl-CoA, an isomerization and an oxidation-decarboxylation, catalyzed by isopropylmalate synthase (IPMS), isopropylmalate isomerase (IPMI, also called a dehydratase) and isopropylmalate dehydrogenase (IPMDH), respectively. Leu biosynthesis is then completed by a transamination step catalyzed by a branched-chain aminotransferase that could be also involved in the formation of the other branched-chain amino acids. The large IPMI subunit is involved in both Leu and glucosinolate metabolism, while the small subunits appear to be specific for each pathway | Arabidopsis thaliana |
| physiological function | an intact IPMI small subunit 1 gene seems to be crucial for the development of mature viable seeds | Arabidopsis thaliana |
| physiological function | function of IPMI large subunit 1 in both the biosynthesis of Leu and in the Met chain elongation pathway of glucosinolate formation | Arabidopsis thaliana |
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