Spermidine/spermine-N1-acetyltransferase 2 is an essential component of the ubiquitin ligase complex that regulates hypoxia-inducible factor 1alpha.
Hypoxia-inducible factor 1 (HIF-1) is a heterodimeric transcription factor that functions as a master regulator of oxygen homeostasis. The HIF-1alpha subunit is subjected to O(2)-dependent prolyl hydroxylation leading to ubiquitination by the von Hippel-Lindau protein (VHL)-Elongin C ubiquitin-ligase complex and degradation by the 26 S proteasome. In this study, we ... demonstrate that spermidine/spermine-N(1)-acetyltransferase (SSAT) 2 plays an essential role in this process. SSAT2 binds to HIF-1alpha, VHL, and Elongin C and promotes ubiquitination of hydroxylated HIF-1alpha by stabilizing the interaction of VHL and Elongin C. Multivalent interactions by SSAT2 provide a mechanism to ensure efficient complex formation, which is necessary for the extremely rapid ubiquitination and degradation of HIF-1alpha that is observed in oxygenated cells.
Mesh Terms:
Acetyltransferases, Anoxia, Cell Line, Genetic Vectors, Glutathione Transferase, Humans, Hypoxia-Inducible Factor 1, alpha Subunit, Models, Biological, Oxygen, Proteasome Endopeptidase Complex, Protein Binding, Transcription Factors, Two-Hybrid System Techniques, Ubiquitin-Protein Ligases, Von Hippel-Lindau Tumor Suppressor Protein
Acetyltransferases, Anoxia, Cell Line, Genetic Vectors, Glutathione Transferase, Humans, Hypoxia-Inducible Factor 1, alpha Subunit, Models, Biological, Oxygen, Proteasome Endopeptidase Complex, Protein Binding, Transcription Factors, Two-Hybrid System Techniques, Ubiquitin-Protein Ligases, Von Hippel-Lindau Tumor Suppressor Protein
J. Biol. Chem.
Date: Aug. 10, 2007
PubMed ID: 17558023
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