Functional redundancy of the zinc fingers of A20 for inhibition of NF-kappaB activation and protein-protein interactions.
The tumor necrosis factor (TNF) inducible protein A20 is a potent inhibitor of nuclear factor-kappaB (IkappaB)-mediated gene expression in response to TNF and several other stimuli. The C-terminal domain of A20 is characterized by seven zinc finger structures. Here, we show that a minimum of four zinc fingers is required to inhibit TNF-induced nuclear factor-kappaB (NF-kappaB) activation to a level that is comparable to that obtained with the wild-type A20 protein. However, there was no strict requirement for a particular zinc finger structure, since a mutant A20 protein containing only the first four zinc fingers was as potent as a mutant protein containing only the last four zinc fingers. A similar functional redundancy of the A20 zinc fingers was also observed for binding of A20 to a number of other proteins, including two novel NF-kappaB inhibitory proteins (ABIN-1, ABIN-2), A20 itself, the anti-apoptotic protein TXBP151, and a regulatory component of the IkappaB kinase complex, IKKgamma. Moreover, we demonstrate that complete loss of binding of any of these proteins correlates with complete loss of A20's ability to inhibit TNF-induced NF-kappaB activation. However, binding of IKKgamma as such is not sufficient for inhibition of NF-kappaB dependent gene expression in response to TNF.
Klinkenberg
M
M
Department of Molecular Biology, Unit for Molecular Signal Transduction in Inflammation, University of Ghent, Flanders Interuniversity Institute for Biotechnology, K.L. Ledeganckstraat 35, B-9000 Ghent, Belgium.
Van Huffel
S
S
Heyninck
K
K
Beyaert
R
R
D000595:Amino Acid Sequence; D002478:Cells, Cultured; D004268:DNA-Binding Proteins; D006801:Humans; D051550:I-kappa B Kinase; D047908:Intracellular Signaling Peptides and Proteins; D008969:Molecular Sequence Data; D016328:NF-kappa B / Q000378:metabolism*; D009687:Nuclear Proteins; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011506:Proteins / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D000072598:Tumor Necrosis Factor alpha-Induced Protein 3; D016335:Zinc Fingers / Q000502:physiology*; D000097782:NF-kappaB-Inducing Kinase
D004268:DNA-Binding Proteins; D051550:I-kappa B Kinase; D047908:Intracellular Signaling Peptides and Proteins; D016328:NF-kappa B; D009687:Nuclear Proteins; D017346:Protein Serine-Threonine Kinases; D011506:Proteins; D000072598:Tumor Necrosis Factor alpha-Induced Protein 3; D000097782:NF-kappaB-Inducing Kinase; C496559:CHUK protein, human; C496560:IKBKB protein, human; C496565:IKBKE protein, human; C076529:TNFAIP3 protein, human