Aspartate-semialdehyde dehydrogenase
Aspartate-beta-semialdehyde dehydrogenase (ASADH) lies at the first branch point in the biosynthetic pathway that converts L-aspartic acid to lysine, isoleucine, methionine, threonine and metabolic intermediates such as diaminopimelic acid. The reaction catalysed is the reductive dephosphorylation of L-beta-aspartyl phosphate to L-aspartate-beta-semialdehyde, in the presence of NADPH. ASADH occurs in plants, most bacteria and fungi.
Reference Protein and Structure
- Sequence
-
P0A9Q9
(1.2.1.11)
(Sequence Homologues)
(PDB Homologues)
- Biological species
-
Escherichia coli K-12 (Bacteria)
- PDB
-
1brm
- ASPARTATE BETA-SEMIALDEHYDE DEHYDROGENASE FROM ESCHERICHIA COLI
(2.5 Å)
- Catalytic CATH Domains
-
3.30.360.10
(see all for 1brm)
Enzyme Reaction (EC:1.2.1.11)
+
+
→
+
+
Alternative enzyme names: L-aspartate-beta-semialdehyde:NADP oxidoreductase (phosporylating), ASA dehydrogenase, Aspartate semialdehyde dehydrogenase, Aspartic beta-semialdehyde dehydrogenase, Aspartic semialdehyde dehydrogenase, L-aspartate-beta-semialdehyde dehydrogenase,
Enzyme Mechanism
Introduction
The mechanism of ASADH is thought to be very similar to that of Glyceraldehyde-3-phosphate dehydrogenase. In the suggested mechanism the cysteine thiolate attacks the substrate carbonyl to form a thioester intermediate. This is followed by the transfer of a hydride to NADP to form NADPH. The oxygen anion of a bound inorganic phosphate attacks the thioester intermediate to expel the cysteine thiolate and to form the phosphorylated product.
Catalytic Residues Roles
| UniProt | PDB* (1brm) | ||
| His274 | His274A | Acts as the general acid/base. | proton shuttle (general acid/base) |
| Arg267 | Arg267A | Acts as a bidentate ligand to the substrate carboxyl group which correctly positions the tetrahedral intermediates during the reaction. | steric role |
| Cys135 | Cys135A | Acts as a nucleophile. | covalent catalysis |
| Gln162 | Gln162A | Helps stabilise the negatively charged intermediates. | electrostatic stabiliser |
*PDB label guide - RESx(y)B(C) - RES: Residue Name; x: Residue ID in PDB file;
y: Residue ID in PDB sequence if different from PDB file; B: PDB Chain;
C: Biological Assembly Chain if different from PDB. If label is "Not Found" it means this residue is not found in the reference PDB.
Chemical Components
References
- Faehnle CR et al. (2006), J Biol Chem, 281, 31031-31040. Examination of Key Intermediates in the Catalytic Cycle of Aspartate-β-semialdehyde Dehydrogenase from a Gram-positive Infectious Bacteria. DOI:10.1074/jbc.m605926200. PMID:16895909.
- Viola RE et al. (2011), J Amino Acids, 2011, 1-11. The Catalytic Machinery of a Key Enzyme in Amino Acid Biosynthesis. DOI:10.4061/2011/352538. PMID:22332000.
- Singh A et al. (2008), J Mol Model, 14, 249-263. Molecular modelling and comparative structural account of aspartyl β-semialdehyde dehydrogenase of Mycobacterium tuberculosis (H37Rv). DOI:10.1007/s00894-008-0267-2. PMID:18236087.
- Blanco J et al. (2004), Acta Crystallogr D Biol Crystallogr, 60, 1388-1395. The role of substrate-binding groups in the mechanism of aspartate-β-semialdehyde dehydrogenase. DOI:10.1107/s0907444904012971. PMID:15272161.
- Blanco J et al. (2004), Acta Crystallogr D Biol Crystallogr, 60, 1808-1815. Critical catalytic functional groups in the mechanism of aspartate-β-semialdehyde dehydrogenase. DOI:10.1107/s0907444904020104. PMID:15388927.
- Blanco J et al. (2003), Proc Natl Acad Sci U S A, 100, 12613-12617. Capture of an intermediate in the catalytic cycle of L-aspartate- -semialdehyde dehydrogenase. DOI:10.1073/pnas.1634958100. PMID:14559965.
- Chassagnole C et al. (2001), Biochem J, 356, 415-423. An integrated study of threonine-pathway enzyme kinetics in Escherichia coli. PMID:11368768.
- Hadfield A et al. (2001), Biochemistry, 40, 14475-14483. Active Site Analysis of the Potential Antimicrobial Target Aspartate Semialdehyde Dehydrogenase. DOI:10.1021/bi015713o.
- Hadfield A et al. (1999), J Mol Biol, 289, 991-1002. Structure of Aspartate-β-semialdehyde Dehydrogenase from Escherichia coli, a Key Enzyme in the Aspartate Family of Amino Acid Biosynthesis. DOI:10.1006/jmbi.1999.2828. PMID:10369777.
- Karsten WE et al. (1992), Biochim Biophys Acta, 1121, 234-238. Identification of an essential cysteine in the reaction catalyzed by aspartate-β-semialdehyde dehydrogenase from Escherichia coli. DOI:10.1016/0167-4838(92)90360-p. PMID:1350921.
Catalytic Residues Roles
| Residue | Roles |
|---|---|
| Arg267A | steric role |
| Cys135A | covalent catalysis |
| His274A | proton shuttle (general acid/base) |
| Gln162A | electrostatic stabiliser |