Q9SA18 · AKH1_ARATH
- ProteinBifunctional aspartokinase/homoserine dehydrogenase 1, chloroplastic
- GeneAKHSDH1
- StatusUniProtKB reviewed (Swiss-Prot)
- Amino acids911 (go to sequence)
- Protein existenceEvidence at protein level
- Annotation score5/5
Function
function
Bifunctional aspartate kinase and homoserine dehydrogenase that catalyzes the first and the third steps toward the synthesis of lysine, methionine and threonine from aspartate.
Catalytic activity
- L-homoserine + NADP+ = H+ + L-aspartate 4-semialdehyde + NADPHThis reaction proceeds in the backward direction.
Cofactor
Note: A sodium ion is seen in the structure; a metal ion may subtly affect the relative position of the nucleotide-binding region to influence enzyme activity, and could increase the stability of the enzyme.
Activity regulation
Inhibition of aspartate kinase activity by threonine and leucine and 3-fold activation by cysteine, isoleucine, valine, serine and alanine at 2.5 mM. Partial inhibition of homoserine dehydrogenase activity by threonine and cysteine (14% of activity remaining at saturation with either amino acid). No synergy between the effectors for both activation or inhibition.
Kinetics
KM | SUBSTRATE | pH | TEMPERATURE[C] | NOTES | EVIDENCE | |
---|---|---|---|---|---|---|
2.6 mM | aspartate for the aspartokinase activity | 8.0 | in the presence of 150 mM KCl, 20 mM MgCl2, 200 uM NADPH 20 mM ATP | |||
2.3 mM | aspartate for the aspartokinase activity | 8.0 | in the presence of 150 mM KCl, 20 mM MgCl2, 200 uM NADPH, 20 mM ATP a saturating concentration of alanine | |||
6.5 mM | ATP for the aspartokinase activity | 8.0 | in the presence of 150 mM KCl, 20 mM MgCl2, 200 uM NADPH 50 mM aspartate | |||
0.48 mM | ATP for the aspartokinase activity | 8.0 | in the presence of 150 mM KCl, 20 mM MgCl2, 200 uM NADPH, 50 mM aspartate a saturating concentration of alanine | |||
290 μM | aspartate semialdehyde for the forward reaction of the homoserine dehydrogenase activity | 8.0 | in the presence of 150 mM KCl 200 uM NADPH |
Pathway
Amino-acid biosynthesis; L-lysine biosynthesis via DAP pathway; (S)-tetrahydrodipicolinate from L-aspartate: step 1/4.
Amino-acid biosynthesis; L-methionine biosynthesis via de novo pathway; L-homoserine from L-aspartate: step 1/3.
Amino-acid biosynthesis; L-methionine biosynthesis via de novo pathway; L-homoserine from L-aspartate: step 3/3.
Amino-acid biosynthesis; L-threonine biosynthesis; L-threonine from L-aspartate: step 1/5.
Amino-acid biosynthesis; L-threonine biosynthesis; L-threonine from L-aspartate: step 3/5.
Features
Showing features for binding site, active site.
Type | ID | Position(s) | Description | |||
---|---|---|---|---|---|---|
Binding site | 563 | NAD+ (UniProtKB | ChEBI) | ||||
Sequence: I | ||||||
Binding site | 563 | NADP+ (UniProtKB | ChEBI) | ||||
Sequence: I | ||||||
Binding site | 563 | NADPH (UniProtKB | ChEBI) | ||||
Sequence: I | ||||||
Binding site | 644 | NAD+ (UniProtKB | ChEBI) | ||||
Sequence: T | ||||||
Binding site | 644 | NADP+ (UniProtKB | ChEBI) | ||||
Sequence: T | ||||||
Binding site | 644 | NADPH (UniProtKB | ChEBI) | ||||
Sequence: T | ||||||
Binding site | 668 | NADP+ (UniProtKB | ChEBI) | ||||
Sequence: K | ||||||
Binding site | 668 | NADPH (UniProtKB | ChEBI) | ||||
Sequence: K | ||||||
Binding site | 695 | Na+ (UniProtKB | ChEBI) | ||||
Sequence: E | ||||||
Binding site | 698 | Na+ (UniProtKB | ChEBI) | ||||
Sequence: V | ||||||
Binding site | 700 | Na+ (UniProtKB | ChEBI) | ||||
Sequence: A | ||||||
Binding site | 702 | Na+ (UniProtKB | ChEBI) | ||||
Sequence: L | ||||||
Binding site | 753 | NADP+ (UniProtKB | ChEBI) | ||||
Sequence: G | ||||||
Binding site | 756 | L-homoserine (UniProtKB | ChEBI) | ||||
Sequence: E | ||||||
Binding site | 756 | NADP+ (UniProtKB | ChEBI) | ||||
Sequence: E | ||||||
Binding site | 767 | L-homoserine (UniProtKB | ChEBI) | ||||
Sequence: D | ||||||
Active site | 771 | Proton donor | ||||
Sequence: K | ||||||
Binding site | 888 | NAD+ (UniProtKB | ChEBI) | ||||
Sequence: G | ||||||
Binding site | 888 | NADP+ (UniProtKB | ChEBI) | ||||
Sequence: G | ||||||
Binding site | 888 | NADPH (UniProtKB | ChEBI) | ||||
Sequence: G |
GO annotations
Aspect | Term | |
---|---|---|
Cellular Component | chloroplast | |
Cellular Component | chloroplast stroma | |
Cellular Component | cytosol | |
Molecular Function | aspartate kinase activity | |
Molecular Function | ATP binding | |
Molecular Function | homoserine dehydrogenase activity | |
Molecular Function | metal ion binding | |
Molecular Function | NAD+ binding | |
Molecular Function | NADP binding | |
Biological Process | homoserine biosynthetic process | |
Biological Process | lysine biosynthetic process via diaminopimelate | |
Biological Process | methionine biosynthetic process | |
Biological Process | threonine biosynthetic process |
Keywords
- Molecular function
- Biological process
- Ligand
Enzyme and pathway databases
Names & Taxonomy
Protein names
- Recommended nameBifunctional aspartokinase/homoserine dehydrogenase 1, chloroplastic
- Short namesAK-HD 1 ; AK-HSDH 1
- Alternative names
Including 2 domains:
- Recommended nameAspartokinase
- EC number
- Recommended nameHomoserine dehydrogenase
- EC number
Gene names
Organism names
- Strain
- Taxonomic lineageEukaryota > Viridiplantae > Streptophyta > Embryophyta > Tracheophyta > Spermatophyta > Magnoliopsida > eudicotyledons > Gunneridae > Pentapetalae > rosids > malvids > Brassicales > Brassicaceae > Camelineae > Arabidopsis
Accessions
- Primary accessionQ9SA18
- Secondary accessions
Proteomes
Organism-specific databases
Genome annotation databases
Subcellular Location
PTM/Processing
Features
Showing features for transit peptide, chain.
Type | ID | Position(s) | Description | |||
---|---|---|---|---|---|---|
Transit peptide | 1-82 | Chloroplast | ||||
Sequence: MPVVSLAKVVTSPAVAGDLAVRVPFIYGKRLVSNRVSFGKLRRRSCIGQCVRSELQSPRVLGSVTDLALDNSVENGHLPKGD | ||||||
Chain | PRO_0000245844 | 83-911 | Bifunctional aspartokinase/homoserine dehydrogenase 1, chloroplastic | |||
Sequence: SWAVHKFGGTCVGNSERIKDVAAVVVKDDSERKLVVVSAMSKVTDMMYDLIHRAESRDDSYLSALSGVLEKHRATAVDLLDGDELSSFLARLNDDINNLKAMLRAIYIAGHATESFSDFVVGHGELWSAQMLAAVVRKSGLDCTWMDARDVLVVIPTSSNQVDPDFVESEKRLEKWFTQNSAKIIIATGFIASTPQNIPTTLKRDGSDFSAAIMSALFRSHQLTIWTDVDGVYSADPRKVSEAVVLKTLSYQEAWEMSYFGANVLHPRTIIPVMKYDIPIVIRNIFNLSAPGTMICRQIDDEDGFKLDAPVKGFATIDNLALVNVEGTGMAGVPGTASAIFSAVKEVGANVIMISQASSEHSVCFAVPEKEVKAVSEALNSRFRQALAGGRLSQIEIIPNCSILAAVGQKMASTPGVSATFFNALAKANINIRAIAQGCSEFNITVVVKREDCIRALRAVHSRFYLSRTTLAVGIIGPGLIGGTLLDQIRDQAAVLKEEFKIDLRVIGITGSSKMLMSESGIDLSRWRELMKEEGEKADMEKFTQYVKGNHFIPNSVMVDCTADADIASCYYDWLLRGIHVVTPNKKANSGPLDQYLKIRDLQRKSYTHYFYEATVGAGLPIISTLRGLLETGDKILRIEGIFSGTLSYLFNNFVGTRSFSEVVAEAKQAGFTEPDPRDDLSGTDVARKVTILARESGLKLDLEGLPVQNLVPKPLQACASAEEFMEKLPQFDEELSKQREEAEAAGEVLRYVGVVDAVEKKGTVELKRYKKDHPFAQLSGADNIIAFTTKRYKEQPLIVRGPGAGAQVTAGGIFSDILRLAFYLGAPS |
Proteomic databases
PTM databases
Expression
Gene expression databases
Structure
Family & Domains
Features
Showing features for region, domain.
Type | ID | Position(s) | Description | |||
---|---|---|---|---|---|---|
Region | 83-331 | Aspartokinase | ||||
Sequence: SWAVHKFGGTCVGNSERIKDVAAVVVKDDSERKLVVVSAMSKVTDMMYDLIHRAESRDDSYLSALSGVLEKHRATAVDLLDGDELSSFLARLNDDINNLKAMLRAIYIAGHATESFSDFVVGHGELWSAQMLAAVVRKSGLDCTWMDARDVLVVIPTSSNQVDPDFVESEKRLEKWFTQNSAKIIIATGFIASTPQNIPTTLKRDGSDFSAAIMSALFRSHQLTIWTDVDGVYSADPRKVSEAVVLKTL | ||||||
Region | 332-557 | Interface | ||||
Sequence: SYQEAWEMSYFGANVLHPRTIIPVMKYDIPIVIRNIFNLSAPGTMICRQIDDEDGFKLDAPVKGFATIDNLALVNVEGTGMAGVPGTASAIFSAVKEVGANVIMISQASSEHSVCFAVPEKEVKAVSEALNSRFRQALAGGRLSQIEIIPNCSILAAVGQKMASTPGVSATFFNALAKANINIRAIAQGCSEFNITVVVKREDCIRALRAVHSRFYLSRTTLAVGI | ||||||
Domain | 407-482 | ACT 1 | ||||
Sequence: VEGTGMAGVPGTASAIFSAVKEVGANVIMISQASSEHSVCFAVPEKEVKAVSEALNSRFRQALAGGRLSQIEIIPN | ||||||
Domain | 488-565 | ACT 2 | ||||
Sequence: AVGQKMASTPGVSATFFNALAKANINIRAIAQGCSEFNITVVVKREDCIRALRAVHSRFYLSRTTLAVGIIGPGLIGG | ||||||
Region | 558-911 | Homoserine dehydrogenase | ||||
Sequence: IGPGLIGGTLLDQIRDQAAVLKEEFKIDLRVIGITGSSKMLMSESGIDLSRWRELMKEEGEKADMEKFTQYVKGNHFIPNSVMVDCTADADIASCYYDWLLRGIHVVTPNKKANSGPLDQYLKIRDLQRKSYTHYFYEATVGAGLPIISTLRGLLETGDKILRIEGIFSGTLSYLFNNFVGTRSFSEVVAEAKQAGFTEPDPRDDLSGTDVARKVTILARESGLKLDLEGLPVQNLVPKPLQACASAEEFMEKLPQFDEELSKQREEAEAAGEVLRYVGVVDAVEKKGTVELKRYKKDHPFAQLSGADNIIAFTTKRYKEQPLIVRGPGAGAQVTAGGIFSDILRLAFYLGAPS |
Sequence similarities
In the N-terminal section; belongs to the aspartokinase family.
In the C-terminal section; belongs to the homoserine dehydrogenase family.
Keywords
- Domain
Phylogenomic databases
Family and domain databases
Sequence
- Sequence statusComplete
- Sequence processingThe displayed sequence is further processed into a mature form.
- Length911
- Mass (Da)99,404
- Last updated2000-05-01 v1
- Checksum95A663413B68585F
Sequence caution
Features
Showing features for sequence conflict.
Type | ID | Position(s) | Description | |||
---|---|---|---|---|---|---|
Sequence conflict | 517 | in Ref. 4; BAC43372 | ||||
Sequence: I → M | ||||||
Sequence conflict | 900 | in Ref. 4; BAC43372 | ||||
Sequence: I → F |
Keywords
- Technical term
Sequence databases
Nucleotide Sequence | Protein Sequence | Molecule Type | Status | |
---|---|---|---|---|
AC004793 EMBL· GenBank· DDBJ | AAD21689.1 EMBL· GenBank· DDBJ | Genomic DNA | ||
AC007654 EMBL· GenBank· DDBJ | AAF24602.1 EMBL· GenBank· DDBJ | Genomic DNA | Sequence problems. | |
CP002684 EMBL· GenBank· DDBJ | AEE31330.1 EMBL· GenBank· DDBJ | Genomic DNA | ||
AK118779 EMBL· GenBank· DDBJ | BAC43372.1 EMBL· GenBank· DDBJ | mRNA | ||
X71364 EMBL· GenBank· DDBJ | CAA50500.2 EMBL· GenBank· DDBJ | Genomic DNA | Sequence problems. |