Structure-based mutagenesis of the substrate-recognition domain of Nrdp1/FLRF identifies the binding site for the receptor tyrosine kinase ErbB3.
The E3 ubiquitin ligase neuregulin receptor degrading protein 1 (Nrdp1) mediates the ligand-independent degradation of the epidermal growth factor receptor family member ErbB3/HER3. By regulating cellular levels of ErbB3, Nrdp1 influences ErbB3-mediated signaling, which is essential for normal vertebrate development. Nrdp1 belongs to the tripartite or RBCC (RING, B-box, coiled-coil) family of ubiquitin ligases in which the RING domain is responsible for ubiquitin ligation and a variable C-terminal region mediates substrate recognition. We report here the 1.95 A crystal structure of the C-terminal domain of Nrdp1 and show that this domain is sufficient to mediate ErbB3 binding. Furthermore, we have used site-directed mutagenesis to map regions of the Nrdp1 surface that are important for interacting with ErbB3 and mediating its degradation in transfected cells. The ErbB3-binding site localizes to a region of Nrdp1 that is conserved from invertebrates to vertebrates, in contrast to ErbB3, which is only found in vertebrates. This observation suggests that Nrdp1 uses a common binding site to recognize its targets in different species.
Bouyain
Samuel
S
Department of Biophysics and Biophysical Chemistry, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
Leahy
Daniel J
DJ
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D003001:Cloning, Molecular; D003460:Crystallization; D018076:DNA, Complementary; D006801:Humans; D008969:Molecular Sequence Data; D016296:Mutagenesis; D011485:Protein Binding; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D044767:Ubiquitin-Protein Ligases / Q000737:chemistry / Q000378:metabolism*
D018076:DNA, Complementary; C452580:RNF41 protein, human; D044767:Ubiquitin-Protein Ligases; D020794:Receptor Protein-Tyrosine Kinases