title: Structural investigations of the p53/p73 homologs from the tunicate species Ciona intestinalis reveal the sequence requirements for the formation of a tetramerization domain.
abstract: Most members of the p53 family of transcription factors form tetramers. Responsible for determining the oligomeric state is a short oligomerization domain consisting of one β-strand and one α-helix. With the exception of human p53 all other family members investigated so far contain a second α-helix as part of their tetramerization domain. Here we have used nuclear magnetic resonance spectroscopy to characterize the oligomerization domains of the two p53-like proteins from the tunicate Ciona intestinalis, representing the closest living relative of vertebrates. Structure determination reveals for one of the two proteins a new type of packing of this second α-helix on the core domain that was not predicted based on the sequence, while the other protein does not form a second helix despite the presence of crucial residues that are conserved in all other family members that form a second helix. By mutational analysis, we identify a proline as well as large hydrophobic residues in the hinge region between both helices as the crucial determinant for the formation of a second helix.
authors.affiliation: Institute of Biophysical Chemistry and Center for Biomolecular Magnetic Resonance, Goethe University, D-60438 Frankfurt/Main, Germany.
authors.forename: Jan
authors.initials: J
authors.lastname: Heering
authors.affiliation: Institute of Organic Chemistry and Chemical Biology and Center for Biomolecular Magnetic Resonance, Goethe University, D-60438 Frankfurt/Main, Germany.
authors.forename: Hendrik R A
authors.initials: HR
authors.lastname: Jonker
authors.affiliation: Institute of Biophysical Chemistry and Center for Biomolecular Magnetic Resonance, Goethe University, D-60438 Frankfurt/Main, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Löhr
authors.affiliation: Institute of Organic Chemistry and Chemical Biology and Center for Biomolecular Magnetic Resonance, Goethe University, D-60438 Frankfurt/Main, Germany.
authors.forename: Harald
authors.initials: H
authors.lastname: Schwalbe
authors.affiliation: Institute of Biophysical Chemistry and Center for Biomolecular Magnetic Resonance, Goethe University, D-60438 Frankfurt/Main, Germany.
authors.forename: Volker
authors.initials: V
authors.lastname: Dötsch
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002938:Ciona intestinalis / Q000737:chemistry*; D004268:DNA-Binding Proteins / Q000737:chemistry*; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D009687:Nuclear Proteins / Q000737:chemistry*; D017510:Protein Folding; D055503:Protein Multimerization; D055550:Protein Stability; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D000072160:Tumor Protein p73; D016159:Tumor Suppressor Protein p53 / Q000737:chemistry*; D025521:Tumor Suppressor Proteins / Q000737:chemistry*
chemical_list: D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; C000606460:TP73 protein, human; D000072160:Tumor Protein p73; D016159:Tumor Suppressor Protein p53; D025521:Tumor Suppressor Proteins
keywords: Ciona intestinalis; NMR structure; oligomerization domain; p53; p63; p73; tetramerization