The tight junction protein occludin and the adherens junction protein alpha-catenin share a common interaction mechanism with ZO-1.
The exact sites, structures, and molecular mechanisms of interaction between junction organizing zona occludence protein 1 (ZO-1) and the tight junction protein occludin or the adherens junction protein alpha-catenin are unknown. Binding studies by surface plasmon resonance spectroscopy and peptide mapping combined with comparative modeling utilizing crystal structures led for the first time to a molecular model revealing the binding of both occludin and alpha-catenin to the same binding site in ZO-1. Our data support a concept that ZO-1 successively associates with alpha-catenin at the adherens junction and occludin at the tight junction. Strong spatial evidence indicates that the occludin C-terminal coiled-coil domain dimerizes and interacts finally as a four-helix bundle with the identified structural motifs in ZO-1. The helix bundle of occludin406-521 and alpha-catenin509-906 interacts with the hinge region (ZO-1591-632 and ZO-1591-622, respectively) and with (ZO-1726-754 and ZO-1756-781) in the GuK domain of ZO-1 containing coiled-coil and alpha-helical structures, respectively. The selectivity of both protein-protein interactions is defined by complementary shapes and charges between the participating epitopes. In conclusion, a common molecular mechanism of forming an intermolecular helical bundle between the hinge region/GuK domain of ZO-1 and alpha-catenin and occludin is identified as a general molecular principle organizing the association of ZO-1 at adherens and tight junctions.
Müller
Sebastian L
SL
Forschungsinstitut für Molekulare Pharmakologie, 13125 Berlin, Charité-Campus Mitte, 10117 Berlin, Germany, and Charité-Campus Benjamin Franklin, 12203 Berlin, Germany.
Portwich
Michael
M
Schmidt
Anke
A
Utepbergenov
Darkhan I
DI
Huber
Otmar
O
Blasig
Ingolf E
IE
Krause
Gerd
G
D022005:Adherens Junctions / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D003598:Cytoskeletal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D019281:Dimerization; D000939:Epitopes / Q000378:metabolism; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D062793:Occludin; D010449:Peptide Mapping; D010750:Phosphoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D017433:Protein Structure, Secondary; D019108:Tight Junctions / Q000378:metabolism*; D062826:Zonula Occludens-1 Protein; D051178:alpha Catenin
C495272:Ctnna1 protein, mouse; D003598:Cytoskeletal Proteins; D000939:Epitopes; D008565:Membrane Proteins; D062793:Occludin; C568986:Ocln protein, mouse; D010750:Phosphoproteins; C569043:Tjp1 protein, mouse; D062826:Zonula Occludens-1 Protein; D051178:alpha Catenin