Structural basis for specific recognition of Lys 63-linked polyubiquitin chains by NZF domains of TAB2 and TAB3.

TAB2 and TAB3 activate the Jun N-terminal kinase and nuclear factor-kappaB pathways through the specific recognition of Lys 63-linked polyubiquitin chains by its Npl4 zinc-finger (NZF) domain. Here we report crystal structures of the TAB2 and TAB3 NZF domains in complex with Lys 63-linked diubiquitin at 1.18 and 1.40 A ...
resolutions, respectively. Both NZF domains bind to the distal ubiquitin through a conserved Thr-Phe dipeptide that has been shown to be important for the interaction of the NZF domain of Npl4 with monoubiquitin. In contrast, a surface specific to TAB2 and TAB3 binds the proximal ubiquitin. Both the distal and proximal binding sites of the TAB2 and TAB3 NZF domains recognize the Ile 44-centred hydrophobic patch on ubiquitin but do not interact with the Lys 63-linked isopeptide bond. Mutagenesis experiments show that both binding sites are required to enable binding of Lys 63-linked diubiquitin. We therefore propose a mechanism for the recognition of Lys 63-linked polyubiquitin chains by TAB2 and TAB3 NZF domains in which diubiquitin units are specifically recognized by a single NZF domain.
Mesh Terms:
Adaptor Proteins, Signal Transducing, Animals, Binding Sites, Crystallography, X-Ray, JNK Mitogen-Activated Protein Kinases, Lysine, Mice, Models, Molecular, NF-kappa B, Polyubiquitin, Protein Binding, Protein Structure, Tertiary, Ubiquitin, Zinc Fingers
EMBO J.
Date: Dec. 16, 2009
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