Phosphorylation of a PDZ domain extension modulates binding affinity and interdomain interactions in postsynaptic density-95 (PSD-95) protein, a membrane-associated guanylate kinase (MAGUK)

J Biol Chem. 2011 Dec 2;286(48):41776-85. doi: 10.1074/jbc.M111.272583. Epub 2011 Sep 30.

Abstract

Postsynaptic density-95 is a multidomain scaffolding protein that recruits glutamate receptors to postsynaptic sites and facilitates signal processing and connection to the cytoskeleton. It is the leading member of the membrane-associated guanylate kinase family of proteins, which are defined by the PSD-95/Discs large/ZO-1 (PDZ)-Src homology 3 (SH3)-guanylate kinase domain sequence. We used NMR to show that phosphorylation of conserved tyrosine 397, which occurs in vivo and is located in an atypical helical extension (α3), initiates a rapid equilibrium of docked and undocked conformations. Undocking reduced ligand binding affinity allosterically and weakened the interaction of PDZ3 with SH3 even though these domains are separated by a ~25-residue linker. Additional phosphorylation at two linker sites further disrupted the interaction, implicating α3 and the linker in tuning interdomain communication. These experiments revealed a novel mode of regulation by a detachable PDZ element and offer a first glimpse at the dynamic interaction of PDZ and SH3-guanylate kinase domains in membrane-associated guanylate kinases.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Allosteric Regulation / physiology
  • Disks Large Homolog 4 Protein
  • Guanylate Kinases / chemistry*
  • Guanylate Kinases / genetics
  • Guanylate Kinases / metabolism
  • Humans
  • Intracellular Signaling Peptides and Proteins / chemistry*
  • Intracellular Signaling Peptides and Proteins / genetics
  • Intracellular Signaling Peptides and Proteins / metabolism
  • Membrane Proteins / chemistry*
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism
  • Nuclear Magnetic Resonance, Biomolecular
  • PDZ Domains
  • Phosphorylation / physiology
  • Structure-Activity Relationship
  • src Homology Domains

Substances

  • DLG4 protein, human
  • Disks Large Homolog 4 Protein
  • Intracellular Signaling Peptides and Proteins
  • Membrane Proteins
  • Guanylate Kinases