title: Structural basis for specific recognition of Lys 63-linked polyubiquitin chains by NZF domains of TAB2 and TAB3.
abstract: 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.
authors.affiliation: Structural Biology Laboratory, Life Science Division, Synchrotron Radiation Research Organization, Institute of Molecular and Cellular Biosciences, The University of Tokyo, Tokyo, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Sato
authors.forename: Azusa
authors.initials: A
authors.lastname: Yoshikawa
authors.forename: Masami
authors.initials: M
authors.lastname: Yamashita
authors.forename: Atsushi
authors.initials: A
authors.lastname: Yamagata
authors.forename: Shuya
authors.initials: S
authors.lastname: Fukai
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000737:chemistry*; D000818:Animals; D001665:Binding Sites; D018360:Crystallography, X-Ray / Q000379:methods; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D008239:Lysine / Q000737:chemistry; D051379:Mice; D008958:Models, Molecular; D016328:NF-kappa B / Q000378:metabolism; D025821:Polyubiquitin / Q000737:chemistry*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D025801:Ubiquitin / Q000737:chemistry; D016335:Zinc Fingers
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D016328:NF-kappa B; C498761:Tab2 protein, mouse; C528083:Tab3 protein, mouse; D025801:Ubiquitin; D025821:Polyubiquitin; D048031:JNK Mitogen-Activated Protein Kinases; D008239:Lysine