Domain-swapped dimerization of the second PDZ domain of ZO2 may provide a structural basis for the polymerization of claudins.
Zonula occludens proteins (ZOs), including ZO1/2/3, are tight junction-associated proteins. Each of them contains three PDZ domains. It has been demonstrated that ZO1 can form either homodimers or heterodimers with ZO2 or ZO3 through the second PDZ domain. However, the underlying structural basis is not well understood. In this study, the solution structure of the second PDZ domain of ZO2 (ZO2-PDZ2) was determined using NMR spectroscopy. The results revealed a novel dimerization mode for PDZ domains via three-dimensional domain swapping, which can be generalized to homodimers of ZO1-PDZ2 or ZO3-PDZ2 and heterodimers of ZO1-PDZ2/ZO2-PDZ2 or ZO1-PDZ2/ZO3-PDZ2 due to high conservation between PDZ2 domains in ZO proteins. Furthermore, GST pulldown experiments and immunoprecipitation studies demonstrated that interactions between ZO1-PDZ2 and ZO2-PDZ2 and their self-associations indeed exist both in vitro and in vivo. Chemical cross-linking and dynamic laser light scattering experiments revealed that both ZO1-PDZ2 and ZO2-PDZ2 can form oligomers in solution. This PDZ domain-mediated oligomerization of ZOs may provide a structural basis for the polymerization of claudins, namely the formation of tight junctions.
Wu
Jiawen
J
Hefei National Laboratory for Physical Sciences at Microscale and School of Life Sciences, Department of Chemical Physics, University of Science and Technology of China, Hefei, Anhui 230026, People's Republic of China.
Yang
Yinshan
Y
Zhang
Jiahai
J
Ji
Peng
P
Du
Wenjing
W
Jiang
Peng
P
Xie
Dinghai
D
Huang
Hongda
H
Wu
Mian
M
Zhang
Guangzhao
G
Wu
Jihui
J
Shi
Yunyu
Y
D000818:Animals; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D019281:Dimerization; D006801:Humans; D008565:Membrane Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D019906:Nuclear Magnetic Resonance, Biomolecular; D010750:Phosphoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding / Q000502:physiology; D017434:Protein Structure, Tertiary / Q000502:physiology; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013329:Structure-Activity Relationship; D019108:Tight Junctions / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D062825:Zonula Occludens Proteins; D062826:Zonula Occludens-1 Protein; D062827:Zonula Occludens-2 Protein
D002352:Carrier Proteins; D008565:Membrane Proteins; D010750:Phosphoproteins; D011994:Recombinant Proteins; C569042:TJP1 protein, human; C569046:TJP2 protein, human; C111873:TJP3 protein, human; D062825:Zonula Occludens Proteins; D062826:Zonula Occludens-1 Protein; D062827:Zonula Occludens-2 Protein