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Literature summary for 2.3.1.57 extracted from

  • Coleman, C.S.; Pegg, A.E.
    Polyamine analogues inhibit the ubiquitination of spermidine/spermine N1-acetyltransferase and prevent its targeting to the proteasome for degradation (2001), Biochem. J., 358, 137-145.
    View publication on PubMedView publication on EuropePMC
Search for more literature for 2.3.1.57

Activating Compound

Activating Compound Comment Organism Structure
additional information enzyme is highly inducible by polyamine analogues such as N1,N12-bis(ethyl)spermine and N1,N11-bis(ethyl)norspermine, they prevent enzyme degradation via the Ub/proteasome pathway, mechanism Homo sapiens

Cloned(Commentary)

Cloned (Comment) Organism
plasmid pSAT9.3, containing SSAT cDNA cloned into Bluescript vector, is used to express the protein from the T7 promoter using rabbit reticulocyte TNT coupled expression system Homo sapiens

Protein Variants

Protein Variants Comment Organism
E152Q mutation disrupts binding of stabilizing N1,N12-bis(ethyl)spermine to enzyme Homo sapiens
E170Stop mutation stabilizes enzyme, due to the lack of ubiquinated complexes Homo sapiens
E171Q mutation results in a marked stabilization of enzyme, due to the lack of formation of high-molecular-mass complexes with ubiquitin Homo sapiens
E172A mutation stabilizes enzyme, due to the lack of ubiquinated complexes Homo sapiens
E173A mutation stabilizes enzyme, due to the lack of ubiquinated complexes Homo sapiens
K111R mutant with the same activity as wild-type enzyme, but reduced half-life Homo sapiens
K141R mutant with 35% of activity of wild-type enzyme, increased Km for spermidine and reduced half-life Homo sapiens
K158R mutant with 139% of activity of wild-type enzyme Homo sapiens
K161R mutant with the same activity as wild-type enzyme Homo sapiens
K166R mutant with 78% of activity of wild-type enzyme Homo sapiens
K22R mutant with 149% of activity of wild-type enzyme, but reduced half-life Homo sapiens
K26R mutant with 120% of activity of wild-type enzyme Homo sapiens
K39R mutant with the same activity as wild-type enzyme Homo sapiens
K3R mutant with 134% of activity of wild-type enzyme Homo sapiens
K61R mutant with the same activity as wild-type enzyme Homo sapiens
K87R mutant with 70% of activity of wild-type enzyme, but significantly longer half-life, suggesting that Lys-87 may be the preferred site for ubiquination Homo sapiens

General Stability

General Stability Organism
native protein conformation is unstable, polyamine analogues such as N1,N12-bis(ethyl)spermine greatly stabilize, conformational changes caused by their binding prevent the efficient polyubiquination of enzyme and therefore its degradation Homo sapiens

KM Value [mM]

KM Value [mM] KM Value Maximum [mM] Substrate Comment Organism Structure
0.05
-
 spermidine wild-type enzyme Homo sapiens
0.39
-
 spermidine K141R mutant Homo sapiens

Molecular Weight [Da]

Molecular Weight [Da] Molecular Weight Maximum [Da] Comment Organism
20000
-
 2 * 20000, subunit size of 171 amino acids Homo sapiens

Natural Substrates/ Products (Substrates)

Natural Substrates Organism Comment (Nat. Sub.) Natural Products Comment (Nat. Pro.) Rev. Reac.
acetyl-CoA + spermidine Homo sapiens catabolism of spermidine and spermine CoA + N1-acetylspermidine
-
 ?
acetyl-CoA + spermine Homo sapiens catabolism of spermidine and spermine CoA + N1-acetylspermine
-
 ?
additional information Homo sapiens polyamine catabolic enzyme ?
-
 ?
additional information Homo sapiens SSAT prevents overaccumulation of higher polyamines from becoming toxic to cell and maintains a balanced ratio of polyamines according to cellular needs ?
-
 ?

Organism

Organism UniProt Comment Textmining
Homo sapiens
-
-
-

Posttranslational Modification

Posttranslational Modification Comment Organism
phosphoprotein purified SSAT is phosphorylated by casein kinase II Homo sapiens

Substrates and Products (Substrate)

Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
acetyl-CoA + spermidine
-
 Homo sapiens CoA + N1-acetylspermidine
-
 ?
acetyl-CoA + spermidine catabolism of spermidine and spermine Homo sapiens CoA + N1-acetylspermidine
-
 ?
acetyl-CoA + spermine
-
 Homo sapiens CoA + N1-acetylspermine
-
 ?
acetyl-CoA + spermine catabolism of spermidine and spermine Homo sapiens CoA + N1-acetylspermine
-
 ?
additional information Lys-141 is the first residue in a KRR motif that makes up part of the active site Homo sapiens ?
-
 ?
additional information polyamine catabolic enzyme Homo sapiens ?
-
 ?
additional information SSAT prevents overaccumulation of higher polyamines from becoming toxic to cell and maintains a balanced ratio of polyamines according to cellular needs Homo sapiens ?
-
 ?

Subunits

Subunits Comment Organism
homodimer 2 * 20000, subunit size of 171 amino acids Homo sapiens

Temperature Optimum [°C]

Temperature Optimum [°C] Temperature Optimum Maximum [°C] Comment Organism
30
-
 assay at Homo sapiens