title: A model for the interaction between NF-kappa-B and ASPP2 suggests an I-kappa-B-like binding mechanism.
abstract: We used computational methods to study the interaction between two key proteins in apoptosis regulation: the transcription factor NF-kappa-B (NFkappaB) and the proapoptotic protein ASPP2. The C-terminus of ASPP2 contains ankyrin repeats and SH3 domains (ASPP2(ANK-SH3)) that mediate interactions with numerous apoptosis-related proteins, including the p65 subunit of NFkappaB (NFkappaB(p65)). Using peptide-based methods, we have recently identified the interaction sites between NFkappaB(p65) and ASPP2(ANK-SH3) (Rotem et al., J Biol Chem 283, 18990-18999). Here we conducted a computational study of protein docking and molecular dynamics to obtain a structural model of the complex between the full length proteins and propose a mechanism for the interaction. We found that ASPP2(ANK-SH3) binds two sites in NFkappaB(p65), at residues 236-253 and 293-313 that contain the nuclear localization signal (NLS). These sites also mediate the binding of NFkappaB to its natural inhibitor IkappaB, which also contains ankyrin repeats. Alignment of the ankyrin repeats of ASPP2(ANK-SH3) and IkappaB revealed that both proteins share highly similar interfaces at their binding sites to NFkappaB. Protein docking of ASPP2(ANK-SH3) and NFkappaB(p65), as well as molecular dynamics simulations of the proteins, provided structural models of the complex that are energetically similar to the NFkappaB-IkappaB determined structure. Our results show that ASPP2(ANK-SH3) binds NFkappaB(p65) in a similar manner to its natural inhibitor IkappaB, suggesting a possible novel role for ASPP2 as an NFkappaB inhibitor.
authors.affiliation: The Institute of Chemistry, The Hebrew University of Jerusalem, Givat Ram, Jerusalem 91904, Israel.
authors.forename: Hadar
authors.initials: H
authors.lastname: Benyamini
authors.forename: Hadas
authors.initials: H
authors.lastname: Leonov
authors.forename: Shahar
authors.initials: S
authors.lastname: Rotem
authors.forename: Chen
authors.initials: C
authors.lastname: Katz
authors.forename: Isaiah T
authors.initials: IT
authors.lastname: Arkin
authors.forename: Assaf
authors.initials: A
authors.lastname: Friedler
mesh_terms: D000465:Algorithms; D017209:Apoptosis; D051017:Apoptosis Regulatory Proteins / Q000737:chemistry*; D001665:Binding Sites; D019295:Computational Biology / Q000379:methods; D003198:Computer Simulation; D003593:Cytoplasm / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D051550:I-kappa B Kinase / Q000737:chemistry*; D016328:NF-kappa B / Q000737:chemistry* / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D055672:Static Electricity; D016159:Tumor Suppressor Protein p53 / Q000737:chemistry
chemical_list: D051017:Apoptosis Regulatory Proteins; D016328:NF-kappa B; C495901:TP53 protein, human; C090468:TP53BP2 protein, human; D016159:Tumor Suppressor Protein p53; D051550:I-kappa B Kinase