The occludin and ZO-1 complex, defined by small angle X-ray scattering and NMR, has implications for modulating tight junction permeability

• DOI: 10.1073/pnas.1121390109
• Publication Date: 2012-06-19T03:15:14Z
• Authors: Brian R. Tash; Maria C. Bewley; Mariano Russo; Jason M. Keil; Kathleen A. Griffin; Jeffrey M. Sundstrom; David A. Antonetti; Fang Tian; John M. Flanagan
• Keywords: Occludin; Small-angle X-ray scattering

Tight junctions (TJs) are dynamic cellular structures that critical for compartmentalizing environments within tissues and regulating transport of small molecules, ions, fluids. Phosphorylation-dependent binding the transmembrane protein occludin to structural organizing ZO-1 contributes regulation barrier properties; however, details their interaction controversial. Using angle X-ray scattering (SAXS), NMR chemical shift perturbation, cross-saturation, in vitro binding, site-directed mutagenesis experiments. we define interface between PDZ3-SH3-U5-GuK (PSG) coiled-coil (CC) domains. The is comprised basic residues PSG an acidic region CC. Complex formation blocked by a peptide (REESEEYM) corresponds CC 468–475 includes previously uncharacterized phosphosite, with phosphorylated version having larger effect. Furthermore, mutation E470 E472 reduces cell border localization occludin. Together, these results localize predominantly helix V GuK domain. This model has important implications phosphorylation-dependent occludin∶ZO-1 complex.