title: Structure and mechanism of the unique C2 domain of Aida.
abstract: Axin interactor, dorsalization-associated (Aida) was identified as a regulatory factor that utilizes its C-terminal region to interact with axis formation inhibitor (Axin). Aida abrogates the Axin-mediated Jun N-terminal kinase activation required for proper dorsalization during zebrafish embryonic development, and thus functions as a proventralization factor. Here, we report the structure of Aida C-terminal fragments, which adopt a conventional C2 domain topology. We also demonstrate that Aida can specifically bind to phosphoinositides in a Ca(2+) -independent manner, and is able to associate with the cell membrane via a novel positively charged surface, namely a basic loop. Mutation of the positively charged patch on the basic loop leads to destabilization of the Aida-membrane association or disruption of the Aida-Axin interaction, resulting in impaired Jun N-terminal kinase inhibition. Together, our findings provide a molecular basis for C2 domain-mediated Aida-membrane and Aida-Axin associations.
  
  
  METHODS
  The atomic coordinates and structure factors of the mouse Aida C2 domain (code: 2QZ5) and the zebrafish Aida C2 domain (code: 2QZQ) have been deposited in the Protein Data Bank (http://www.rcsb.org/)
  AIDA physically interacts with Axin by anti tag coimmunoprecipitation (View interaction).
authors.affiliation: MOE Key Laboratory of Protein Sciences and Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, China; Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing, China.
authors.forename: Li-Sha
authors.initials: LS
authors.lastname: Zheng
authors.forename: Yi-Tong
authors.initials: YT
authors.lastname: Liu
authors.forename: Lei
authors.initials: L
authors.lastname: Chen
authors.forename: Ying
authors.initials: Y
authors.lastname: Wang
authors.forename: Yan-Ning
authors.initials: YN
authors.lastname: Rui
authors.forename: Hui-Zhe
authors.initials: HZ
authors.lastname: Huang
authors.forename: Shu-Yong
authors.initials: SY
authors.lastname: Lin
authors.forename: Jue
authors.initials: J
authors.lastname: Wang
authors.forename: Zhi-Xin
authors.initials: ZX
authors.lastname: Wang
authors.forename: Sheng-Cai
authors.initials: SC
authors.lastname: Lin
authors.forename: Jia-Wei
authors.initials: JW
authors.lastname: Wu
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D060466:Axin Protein / Q000737:chemistry* / Q000378:metabolism; D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism*; D002352:Carrier Proteins / Q000737:chemistry* / Q000378:metabolism; D002942:Circular Dichroism; D003460:Crystallization; D018360:Crystallography, X-Ray; D057809:HEK293 Cells; D006801:Humans; D047468:Immunoprecipitation; D048670:MAP Kinase Kinase 4 / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D010716:Phosphatidylinositols / Q000378:metabolism*; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D015027:Zebrafish / Q000254:growth & development / Q000378:metabolism*; D029961:Zebrafish Proteins / Q000737:chemistry* / Q000378:metabolism
chemical_list: C522596:Aida protein, zebrafish; D060466:Axin Protein; D002352:Carrier Proteins; D010716:Phosphatidylinositols; D029961:Zebrafish Proteins; D048670:MAP Kinase Kinase 4; D002118:Calcium
keywords: C2 domain; Jun N-terminal kinase (JNK); axin interactor, dorsalization-associated (Aida); axis formation inhibitor (Axin); membrane proteins