Specificity and autoregulation of Notch binding by tandem WW domains in suppressor of Deltex.
WW domains target proline-tyrosine (PY) motifs and frequently function as tandem pairs. When studied in isolation, single WW domains are notably promiscuous and regulatory mechanisms are undoubtedly required to ensure selective interactions. Here, we show that the fourth WW domain (WW4) of Suppressor of Deltex, a modular Nedd4-like protein that down-regulates the Notch receptor, is the primary mediator of a direct interaction with a Notch-PY motif. A natural Trp to Phe substitution in WW4 reduces its affinity for general PY sequences and enhances selective interaction with the Notch-PY motif via compensatory specificity-determining interactions with PY-flanking residues. When WW4 is paired with WW3, domain-domain association, impeding proper folding, competes with Notch-PY binding to WW4. This novel mode of autoinhibition is relieved by binding of another ligand to WW3. Such cooperativity may facilitate the transient regulatory interactions observed in vivo between Su(dx) and Notch in the endocytic pathway. The highly conserved tandem arrangement of WW domains in Nedd4 proteins, and similar arrangements in more diverse proteins, suggests domain-domain communication may be integral to regulation of their associated cellular activities.
Faculty of Life Sciences, Manchester Interdisciplinary Biocentre, University of Manchester, 131 Princess Street, Manchester M1 7DN.
Martin D
MD
Jennings
Faculty of Life Sciences, Manchester Interdisciplinary Biocentre, University of Manchester, 131 Princess Street, Manchester M1 7DN.
Richard T
RT
Blankley
Faculty of Life Sciences, Michael Smith Building, University of Manchester, Manchester M13 9PT, United Kingdom. Electronic address: mbaron@manchester.ac.uk.
Martin
M
Baron
Faculty of Life Sciences, Manchester Interdisciplinary Biocentre, University of Manchester, 131 Princess Street, Manchester M1 7DN. Electronic address: a.golovanov@manchester.ac.uk.
Alexander P
AP
Golovanov
Faculty of Life Sciences, Manchester Interdisciplinary Biocentre, University of Manchester, 131 Princess Street, Manchester M1 7DN. Electronic address: j.avis@manchester.ac.uk.
Johanna M
JM
Avis
D020816:Amino Acid Motifs / Q000502:physiology; D000818:Animals; D029721:Drosophila Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D004331:Drosophila melanogaster / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D004705:Endocytosis / Q000502:physiology; D056827:Endosomal Sorting Complexes Required for Transport; D008565:Membrane Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D000075702:Nedd4 Ubiquitin Protein Ligases; D011485:Protein Binding / Q000502:physiology; D017434:Protein Structure, Tertiary / Q000502:physiology; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013329:Structure-Activity Relationship; D044767:Ubiquitin-Protein Ligases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
C086679:DX protein, Drosophila; D029721:Drosophila Proteins; D056827:Endosomal Sorting Complexes Required for Transport; D008565:Membrane Proteins; D011994:Recombinant Proteins; D000075702:Nedd4 Ubiquitin Protein Ligases; C119838:Su(dx) protein, Drosophila; D044767:Ubiquitin-Protein Ligases