The PDZ2 domain of zonula occludens-1 and -2 is a phosphoinositide binding domain.
Zonula occludens proteins (ZO) are postsynaptic density protein-95 discs large-zonula occludens (PDZ) domain-containing proteins that play a fundamental role in the assembly of tight junctions and establishment of cell polarity. Here, we show that the second PDZ domain of ZO-1 and ZO-2 binds phosphoinositides (PtdInsP) and we identified critical residues involved in the interaction. Furthermore, peptide and PtdInsP binding of ZO PDZ2 domains are mutually exclusive. Although lipid binding does not seem to be required for plasma membrane localisation of ZO-1, phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P (2)) binding to the PDZ2 domain of ZO-2 regulates ZO-2 recruitment to nuclear speckles. Knockdown of ZO-2 expression disrupts speckle morphology, indicating that ZO-2 might play an active role in formation and stabilisation of these subnuclear structures. This study shows for the first time that ZO isoforms bind PtdInsPs and offers an alternative regulatory mechanism for the formation and stabilisation of protein complexes in the nucleus.
Meerschaert
Kris
K
Department of Medical Protein Research, VIB, 9000 Ghent, Belgium.
Tun
Moe Phyu
MP
Remue
Eline
E
De Ganck
Ariane
A
Boucherie
Ciska
C
Vanloo
Berlinda
B
Degeest
Gisèle
G
Vandekerckhove
Joël
J
Zimmermann
Pascale
P
Bhardwaj
Nitin
N
Lu
Hui
H
Cho
Wonhwa
W
Gettemans
Jan
J
D019943:Amino Acid Substitution; D000818:Animals; D001665:Binding Sites; D015153:Blotting, Western; D002460:Cell Line; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D008958:Models, Molecular; D009154:Mutation; D054731:PDZ Domains; D019269:Phosphatidylinositol 4,5-Diphosphate; D018129:Phosphatidylinositol Phosphates / Q000378:metabolism; D010716:Phosphatidylinositols / Q000737:chemistry / Q000378:metabolism*; D010750:Phosphoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D034622:RNA Interference; D020349:Surface Plasmon Resonance; D062826:Zonula Occludens-1 Protein; D062827:Zonula Occludens-2 Protein
D008565:Membrane Proteins; D019269:Phosphatidylinositol 4,5-Diphosphate; D018129:Phosphatidylinositol Phosphates; D010716:Phosphatidylinositols; D010750:Phosphoproteins; C569042:TJP1 protein, human; C569046:TJP2 protein, human; D062826:Zonula Occludens-1 Protein; D062827:Zonula Occludens-2 Protein; D049452:Green Fluorescent Proteins