Structure of an Enzyme-Derived Phosphoprotein Recognition Domain

by Christopher A. Johnston, Chris Q. Doe, Kenneth E. Prehoda

Membrane Associated Guanylate Kinases (MAGUKs) contain a protein interaction domain (GK^dom) derived from the enzyme Guanylate Kinase (GK^enz). Here we show that GK^dom from the MAGUK Discs large (Dlg) is a phosphoprotein recognition domain, specifically recognizing the phosphorylated form of the mitotic spindle orientation protein Partner of Inscuteable (Pins). We determined the structure of the Dlg-Pins complex to understand the dramatic transition from nucleotide kinase to phosphoprotein recognition domain. The structure reveals that the region of the GK^dom that once served as the GMP binding domain (GBD) has been co-opted for protein interaction. Pins makes significantly more contact with the GBD than does GMP, but primarily with residues that are conserved between enzyme and domain revealing the versatility of the GBD as a platform for nucleotide and protein interactions. Mutational analysis reveals that the GBD is also used to bind the GK ligand MAP1a, suggesting that this is a common mode of MAGUK complex assembly. The GK^enz undergoes a dramatic closing reaction upon GMP binding but the protein-bound GK^dom remains in the ‘open’ conformation indicating that the dramatic conformational change has been lost in the conversion from nucleotide kinase to phosphoprotein recognition domain.

For the full article visit: Structure of an Enzyme-Derived Phosphoprotein Recognition Domain
Syndicated from:PLoS ONE

Article is licensed under a Creative Commons Attribution License.