Protein interacting with C-kinase 1 (PICK1) binding promiscuity relies on unconventional PSD-95/Discs-Large/ZO-1 homology (PDZ) binding modes for nonclass II PDZ ligands

TY - JOUR

T1 - Protein interacting with C-kinase 1 (PICK1) binding promiscuity relies on unconventional PSD-95/Discs-Large/ZO-1 homology (PDZ) binding modes for nonclass II PDZ ligands

AU - Erlendsson, Simon

AU - Rathje, Mette

AU - Heiðarsson, Pétur Orri

AU - Poulsen, Flemming Martin

AU - Madsen, Kenneth Lindegaard

AU - Teilum, Kaare

AU - Gether, Ulrik

PY - 2014

Y1 - 2014

N2 - PDZ domain proteins control multiple cellular functions by governing assembly of protein complexes. It remains unknown why individual PDZ domains can bind the extreme C terminus of very diverse binding partners and maintain selectivity. By employing NMR spectroscopy, together with molecular modeling, mutational analysis, and fluorescent polarization binding experiments, we identify here three structural mechanisms explaining why the PDZ domain of PICK1 selectively binds >30 receptors, transporters, and kinases. Class II ligands, including the dopamine transporter, adopt a canonical binding mode with promiscuity obtained via differential packing in the binding groove. Class I ligands, such as protein kinase Cα, depend on residues upstream from the canonical binding sequence that are likely to interact with flexible loop residues of the PDZ domain. Finally, we obtain evidence that the unconventional ligand ASIC1a has a dual binding mode involving a canonical insertion and a noncanonical internal insertion with the two C-terminal residues forming interactions outside the groove. Together with an evolutionary analysis, the data show how unconventional binding modes might evolve for a protein recognition domain to expand the repertoire of functionally important interactions.

AB - PDZ domain proteins control multiple cellular functions by governing assembly of protein complexes. It remains unknown why individual PDZ domains can bind the extreme C terminus of very diverse binding partners and maintain selectivity. By employing NMR spectroscopy, together with molecular modeling, mutational analysis, and fluorescent polarization binding experiments, we identify here three structural mechanisms explaining why the PDZ domain of PICK1 selectively binds >30 receptors, transporters, and kinases. Class II ligands, including the dopamine transporter, adopt a canonical binding mode with promiscuity obtained via differential packing in the binding groove. Class I ligands, such as protein kinase Cα, depend on residues upstream from the canonical binding sequence that are likely to interact with flexible loop residues of the PDZ domain. Finally, we obtain evidence that the unconventional ligand ASIC1a has a dual binding mode involving a canonical insertion and a noncanonical internal insertion with the two C-terminal residues forming interactions outside the groove. Together with an evolutionary analysis, the data show how unconventional binding modes might evolve for a protein recognition domain to expand the repertoire of functionally important interactions.

U2 - 10.1074/jbc.M114.548743

DO - 10.1074/jbc.M114.548743

M3 - Journal article

C2 - 25023278

SN - 0021-9258

VL - 289

SP - 25327

EP - 25340

JO - Journal of Biological Chemistry

JF - Journal of Biological Chemistry

IS - 36

ER -