Crystallization (Comment) | Organism |
---|---|
purified PpALDH21 in apoform, and in complex with succinate and NADP+, X-ray diffraction structure determination and analysis at 2.15-2.30 A resolution, structure modeling | Physcomitrium patens |
Protein Variants | Comment | Organism |
---|---|---|
N175A | site-directed mutagenesis, the mutant shows reduced activity compared tow wild-type enzyme | Physcomitrium patens |
R121A | site-directed mutagenesis, almost inactive mutant | Physcomitrium patens |
R228A | site-directed mutagenesis, the mutation results in 37fold lower catalytic efficiency value (kcat/Km) for NADP+, but only fourfold lower value for NAD+ compared to wild-type | Physcomitrium patens |
R457A | site-directed mutagenesis, almost inactive mutant | Physcomitrium patens |
Y296A | site-directed mutagenesis, the mutant shows reduced activity compared tow wild-type enzyme | Physcomitrium patens |
KM Value [mM] | KM Value Maximum [mM] | Substrate | Comment | Organism | Structure |
---|---|---|---|---|---|
0.024 | - |
NADP+ | recombinant wild-type enzyme, pH 8.2, 25°C, with succinate semialdehyde | Physcomitrium patens | |
0.127 | - |
succinate semialdehyde | recombinant mutant R228A, pH 8.2, 25°C, with NADP+ | Physcomitrium patens | |
0.127 | - |
succinate semialdehyde | recombinant mutant Y296A, pH 8.2, 25°C, with NADP+ | Physcomitrium patens | |
0.135 | - |
succinate semialdehyde | recombinant mutant R457A, pH 8.2, 25°C, with NADP+ | Physcomitrium patens | |
0.181 | - |
succinate semialdehyde | recombinant wild-type enzyme, pH 8.2, 25°C, with NADP+ | Physcomitrium patens | |
0.268 | - |
succinate semialdehyde | recombinant mutant R121A, pH 8.2, 25°C, with NADP+ | Physcomitrium patens | |
0.375 | - |
NADP+ | recombinant mutant R228A, pH 8.2, 25°C, with succinate semialdehyde | Physcomitrium patens | |
0.551 | - |
Glutaric semialdehyde | recombinant wild-type enzyme, pH 8.2, 25°C, with NADP+ | Physcomitrium patens | |
1.49 | - |
succinate semialdehyde | recombinant mutant N175A, pH 8.2, 25°C, with NADP+ | Physcomitrium patens | |
5.37 | - |
NAD+ | recombinant wild-type enzyme, pH 8.2, 25°C, with succinate semialdehyde | Physcomitrium patens | |
8.44 | - |
NAD+ | recombinant mutant R228A, pH 8.2, 25°C, with succinate semialdehyde | Physcomitrium patens |
Localization | Comment | Organism | GeneOntology No. | Textmining |
---|---|---|---|---|
cytosol | - |
Physcomitrium patens | 5829 | - |
Natural Substrates | Organism | Comment (Nat. Sub.) | Natural Products | Comment (Nat. Pro.) | Rev. | Reac. |
---|---|---|---|---|---|---|
succinate semialdehyde + NADP+ + H2O | Physcomitrium patens | - |
succinate + NADPH + 2 H+ | - |
? |
Organism | UniProt | Comment | Textmining |
---|---|---|---|
Physcomitrium patens | A9SS48 | - |
- |
Reaction | Comment | Organism | Reaction ID |
---|---|---|---|
succinate semialdehyde + NADP+ + H2O = succinate + NADPH + 2 H+ | two arginine residues at positions 121 and 457 are both essential for the catalytic activity of ALDH21 and for the binding of SSAL | Physcomitrium patens |
Substrates | Comment Substrates | Organism | Products | Comment (Products) | Rev. | Reac. |
---|---|---|---|---|---|---|
glutaric semialdehyde + NADP+ + H2O | - |
Physcomitrium patens | glutarate + NADPH + 2 H+ | - |
? | |
additional information | glutaric semialdehyde (GRSAL) is the second-best substrate, but it is oxidized at only 1.2% rate compared with succinate semialdehyde | Physcomitrium patens | ? | - |
- |
|
succinate semialdehyde + NAD+ + H2O | poor cofactor for the wild-type enzyme, but is utilized by enzyme mutants, overview | Physcomitrium patens | succinate + NADH + 2 H+ | - |
? | |
succinate semialdehyde + NADP+ + H2O | - |
Physcomitrium patens | succinate + NADPH + 2 H+ | - |
? | |
succinate semialdehyde + NADP+ + H2O | specific for | Physcomitrium patens | succinate + NADPH + 2 H+ | - |
? |
Subunits | Comment | Organism |
---|---|---|
tetramer | - |
Physcomitrium patens |
Synonyms | Comment | Organism |
---|---|---|
ALDH21 | - |
Physcomitrium patens |
NADP+-dependent succinic semialdehyde dehydrogenase | - |
Physcomitrium patens |
PpSSALDH | - |
Physcomitrium patens |
SSALDH | - |
Physcomitrium patens |
Temperature Optimum [°C] | Temperature Optimum Maximum [°C] | Comment | Organism |
---|---|---|---|
25 | - |
assay at | Physcomitrium patens |
Turnover Number Minimum [1/s] | Turnover Number Maximum [1/s] | Substrate | Comment | Organism | Structure |
---|---|---|---|---|---|
0.02 | - |
succinate semialdehyde | recombinant mutant R121A, pH 8.2, 25°C, with NADP+ | Physcomitrium patens | |
0.02 | - |
succinate semialdehyde | recombinant mutant R457A, pH 8.2, 25°C, with NADP+ | Physcomitrium patens | |
0.27 | - |
Glutaric semialdehyde | recombinant wild-type enzyme, pH 8.2, 25°C, with NADP+ | Physcomitrium patens | |
1.2 | - |
NAD+ | recombinant mutant R228A, pH 8.2, 25°C, with succinate semialdehyde | Physcomitrium patens | |
3.3 | - |
NAD+ | recombinant wild-type enzyme, pH 8.2, 25°C, with succinate semialdehyde | Physcomitrium patens | |
5.7 | - |
succinate semialdehyde | recombinant mutant R228A, pH 8.2, 25°C, with NADP+ | Physcomitrium patens | |
6.4 | - |
NADP+ | recombinant mutant R228A, pH 8.2, 25°C, with succinate semialdehyde | Physcomitrium patens | |
7.1 | - |
succinate semialdehyde | recombinant mutant Y296A, pH 8.2, 25°C, with NADP+ | Physcomitrium patens | |
12.5 | - |
succinate semialdehyde | recombinant mutant N175A, pH 8.2, 25°C, with NADP+ | Physcomitrium patens | |
15.2 | - |
NADP+ | recombinant wild-type enzyme, pH 8.2, 25°C, with succinate semialdehyde | Physcomitrium patens | |
15.8 | - |
succinate semialdehyde | recombinant wild-type enzyme, pH 8.2, 25°C, with NADP+ | Physcomitrium patens |
pH Optimum Minimum | pH Optimum Maximum | Comment | Organism |
---|---|---|---|
8.2 | - |
with cofactor NADP+ | Physcomitrium patens |
pH Minimum | pH Maximum | Comment | Organism |
---|---|---|---|
6 | 9.5 | 50% of maximal activity within this range, pH-profile overview | Physcomitrium patens |
Cofactor | Comment | Organism | Structure |
---|---|---|---|
additional information | NAD+ is a very poor coenzyme for ALDH21, the activity with NAD+ is only about 3% of that with NADP+ | Physcomitrium patens | |
NADP+ | preferred cofactor, structural comparison between the apoform and the coenzyme complex reveal that NADP+ binding induces a conformational change of the loop carrying Arg228, which seals the NADP+ in the coenzyme cavity via its 2'-phosphate and alpha-phosphate groups. The presence of a serine residue (Ser197) in PpALDH21 allows for binding of the 2'-phosphate group of NADP+ | Physcomitrium patens |
General Information | Comment | Organism |
---|---|---|
malfunction | both R121A and R457A variants are almost inactive, demonstrating a key role of each arginine in catalysis | Physcomitrium patens |
metabolism | the enzyme is involved in the GABA shunt pathway, GABA shunt reactions from glutamate to succinate might appear in cytosol in addition to mitochondria making the GABA shunt pathway much more diverse | Physcomitrium patens |
additional information | the crystal structure with the bound product succinate shows that its carboxylate group establishes salt bridges with both Arg121 and Arg457, and a hydrogen bond with Tyr296. While both arginine residues are pre-formed for substrate/product binding, Tyr296 moves by more than 1.0 A. Key role of R121 and R457 residues in catalysis. Structure-function analysis, overview | Physcomitrium patens |
physiological function | ALDH21 from the moss Physcomitrella patens codes for a tetrameric NADP+-dependent succinic semialdehyde dehydrogenase (SSALDH), which converts succinate semialdehyde, an intermediate of the gamma-aminobutyric acid (GABA) shunt pathway, into succinate in the cytosol | Physcomitrium patens |
kcat/KM Value [1/mMs-1] | kcat/KM Value Maximum [1/mMs-1] | Substrate | Comment | Organism | Structure |
---|---|---|---|---|---|
0.075 | - |
succinate semialdehyde | recombinant mutant R121A, pH 8.2, 25°C, with NADP+ | Physcomitrium patens | |
0.142 | - |
NAD+ | recombinant mutant R228A, pH 8.2, 25°C, with succinate semialdehyde | Physcomitrium patens | |
0.148 | - |
succinate semialdehyde | recombinant mutant R457A, pH 8.2, 25°C, with NADP+ | Physcomitrium patens | |
0.49 | - |
Glutaric semialdehyde | recombinant wild-type enzyme, pH 8.2, 25°C, with NADP+ | Physcomitrium patens | |
0.615 | - |
NAD+ | recombinant wild-type enzyme, pH 8.2, 25°C, with succinate semialdehyde | Physcomitrium patens | |
8.39 | - |
succinate semialdehyde | recombinant mutant N175A, pH 8.2, 25°C, with NADP+ | Physcomitrium patens | |
17.07 | - |
NADP+ | recombinant mutant R228A, pH 8.2, 25°C, with succinate semialdehyde | Physcomitrium patens | |
44.88 | - |
succinate semialdehyde | recombinant mutant R228A, pH 8.2, 25°C, with NADP+ | Physcomitrium patens | |
55.91 | - |
succinate semialdehyde | recombinant mutant Y296A, pH 8.2, 25°C, with NADP+ | Physcomitrium patens | |
87.29 | - |
succinate semialdehyde | recombinant wild-type enzyme, pH 8.2, 25°C, with NADP+ | Physcomitrium patens | |
633.3 | - |
NADP+ | recombinant wild-type enzyme, pH 8.2, 25°C, with succinate semialdehyde | Physcomitrium patens |