Gold compound auranofin inhibits IkappaB kinase (IKK) by modifying Cys-179 of IKKbeta subunit.
Antirheumatic gold compounds have been shown to inhibit NF-kappaB activation by blocking IkappaB kinase (IKK) activity. To examine the possible inhibitory mechanism of gold compounds, we expressed wild type and mutant forms of IKKalpha and beta subunits in COS-7 cells and determined the effect of gold on the activity of these enzymes both in vivo and in vitro. Substitution of Cys-179 of IKKbeta with alanine (C179A) rendered the enzyme to become resistant to inhibition by a gold compound auranofin, however, similar protective effect was not observed with an equivalent level of IKKalpha (C178A) mutant expressed in the cells. Auranofin inhibited constitutively active IKKalpha and beta and variants; IKKalpha (S176E, S180E) or IKKbeta (S177E, S181E), suggesting that gold directly cause inhibition of activated enzyme. The different inhibitory effect of auranofin on IKKalpha (C178A) and IKKbeta (C179A) mutants indicates that gold could inhibit the two subunits of IKK in a different mode, and the inhibition of NF-kappaB and IKK activation induced by inflammatory signals in gold-treated cells appears through its interaction with Cys-179 of IKKbeta.
Jeon
Kye-Im
KI
Department of Biochemistry, College of Medicine The Catholic University of Korea 505 Banpo-dong, Seocho-gu, Seoul 137-701, Korea.
Byun
Mi-Sun
MS
Jue
Dae-Myung
DM
D019943:Amino Acid Substitution; D000818:Animals; D001310:Auranofin / Q000494:pharmacology*; D019556:COS Cells; D003545:Cysteine / Q000235:genetics / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects; D017612:Gold Compounds / Q000494:pharmacology*; D051550:I-kappa B Kinase; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D021122:Protein Subunits / Q000737:chemistry; D013438:Sulfhydryl Compounds / Q000494:pharmacology
D017612:Gold Compounds; D021122:Protein Subunits; D013438:Sulfhydryl Compounds; D001310:Auranofin; D017346:Protein Serine-Threonine Kinases; D051550:I-kappa B Kinase; D003545:Cysteine