Solution structure of a Nedd4 WW domain-ENaC peptide complex.
Nedd4 is a ubiquitin protein ligase composed of a C2 domain, three (or four) WW domains and a ubiquitin ligase Hect domain. Nedd4 was demonstrated to bind the epithelial sodium channel (alphabetagammaENaC), by association of its WW domains with PY motifs (XPPXY) present in each ENaC subunit, and to regulate the cell surface stability of the channel. The PY motif of betaENaC is deleted or mutated in Liddle syndrome, a hereditary form of hypertension caused by elevated ENaC activity. Here we report the solution structure of the third WW domain of Nedd4 complexed to the PY motif-containing region of betaENaC (TLPIPGTPPPNYDSL, referred to as betaP2). A polyproline type II helical conformation is adopted by the PPPN sequence. Unexpectedly, the C-terminal sequence YDSL forms a helical turn and both the tyrosine and the C-terminal leucine contact the WW domain. This is unlike other proline-rich peptides complexed to WW domains, which bind in an extended conformation and lack molecular interactions with residues C-terminal to the tyrosine or the structurally equivalent residue in non-PY motif WW domain targets. The Nedd4 WW domain-ENaC betaP2 peptide structure expands our understanding of the mechanisms involved in WW domain-ligand recognition and the molecular basis of Liddle syndrome.
Kanelis
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Programmes in Structural Biology and Biochemistry, Hospital for Sick Children, Toronto, Ontario M5G 1X8, Canada.
Rotin
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Forman-Kay
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D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002135:Calcium-Binding Proteins / Q000737:chemistry* / Q000378:metabolism*; D056827:Endosomal Sorting Complexes Required for Transport; D053503:Epithelial Sodium Channels; D008025:Ligases / Q000737:chemistry* / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D000075702:Nedd4 Ubiquitin Protein Ligases; D019906:Nuclear Magnetic Resonance, Biomolecular; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D021122:Protein Subunits; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000378:metabolism; D016415:Sequence Alignment; D015222:Sodium Channels / Q000737:chemistry* / Q000378:metabolism*; D012996:Solutions; D044767:Ubiquitin-Protein Ligases
D002135:Calcium-Binding Proteins; D056827:Endosomal Sorting Complexes Required for Transport; D053503:Epithelial Sodium Channels; D010446:Peptide Fragments; D021122:Protein Subunits; D011993:Recombinant Fusion Proteins; D015222:Sodium Channels; D012996:Solutions; C000618479:NEDD4L protein, rat; D000075702:Nedd4 Ubiquitin Protein Ligases; C000618484:Nedd4 protein, rat; D044767:Ubiquitin-Protein Ligases; D008025:Ligases