Structural basis for the differential interaction of Scribble PDZ domains with the guanine nucleotide exchange factor β-PIX.
Scribble is a highly conserved protein regulator of cell polarity that has been demonstrated to function as a tumor suppressor or, conversely, as an oncogene in a context-dependent manner, and it also controls many physiological processes ranging from immunity to memory. Scribble consists of a leucine-rich repeat domain and four PDZ domains, with the latter being responsible for most of Scribble's complex formation with other proteins. Given the similarities of the Scribble PDZ domain sequences in their binding grooves, it is common for these domains to show overlapping preferences for the same ligand. Yet, Scribble PDZ domains can still exhibit unique binding profiles toward other ligands. This raises the fundamental question as to how these PDZ domains discriminate ligands and exert specificities in Scribble complex formation. To better understand how Scribble PDZ domains direct cell polarity signaling, we investigated here their interactions with the well-characterized Scribble binding partner β-PIX, a guanine nucleotide exchange factor. We report the interaction profiles of all isolated Scribble PDZ domains with a β-PIX peptide. We show that Scribble PDZ1 and PDZ3 are the major interactors with β-PIX and reveal a distinct binding hierarchy in the interactions between the individual Scribble PDZ domains and β-PIX. Furthermore, using crystal structures of PDZ1 and PDZ3 bound to β-PIX, we define the structural basis for Scribble's ability to specifically engage β-PIX via its PDZ domains and provide a mechanistic platform for understanding Scribble-β-PIX-coordinated cellular functions such as directional cell migration.
['Lim|Krystle Y B|KYB|', 'Gödde|Nathan J|NJ|', 'Humbert|Patrick O|PO|', 'Kvansakul|Marc|M|0000-0003-2639-2498']
D000595:Amino Acid Sequence D019943:Amino Acid Substitution D001665:Binding Sites D002151:Calorimetry D017124:Conserved Sequence D018360:Crystallography, X-Ray D057809:HEK293 Cells D006801:Humans D007700:Kinetics D008024:Ligands D008565:Membrane Proteins D008958:Models, Molecular D009154:Mutation D054731:PDZ Domains D010446:Peptide Fragments D011487:Protein Conformation D011993:Recombinant Fusion Proteins D011994:Recombinant Proteins D064067:Rho Guanine Nucleotide Exchange Factors D016415:Sequence Alignment D025521:Tumor Suppressor Proteins
Scribble PDZ domain β-pix cell polarity cell migration X-ray crystallography