Assaf Friedler

Institute of Chemistry
The Hebrew University, Jerusalem 91904, Israel
Tel: 972-2-6585746; fax: 972-2-6585345
Email: assaf@chem.ch.huji.ac.il
Website: http://chem.ch.huji.ac.il/~assaf

Using peptides to study protein - protein interactions: a basis for drug design

Our research deals with quantitative analysis of protein-protein interactions at the molecular level as a basis for designing drug leads that affect the activity of proteins involved in cancer and AIDS. To achieve these goals, we developed an interdisciplinary experimental platform on combining chemistry, biophysics and biology. Some projects ongoing in our lab are:

The "shiftide" concept, by which peptides are used to modulate protein oligomerization for therapeutic purposes
About 35% of proteins in the cytoplasm act as oligomers and many of them exist in equilibrium between active and non-active oligomeric forms. Specific binding of a peptide to one of these oligomeric states will stabilize it and shift the oligomerization equilibrium of the protein towards it. This may result in inhibition or activation of the protein, depending on the oligomeric state targeted. The concept was first successfully demonstrated for inhibiting the HIV-1 integrase protein (Hayouka et al., PNAS 2007) as a novel approach for anti-AIDS therapy. Since then it was demonstrated as a general concept for inhibiting or activating other proteins such as non-muscle myosin II and the tumor suppressor protein p53. The work was recognized worldwide, including an ERC starting grant for Assaf friedler for the shiftides project in 2007 and the Israel chemical society prize for the outstanding young scientist in 2009. The shiftides approach is a general new concept that can be generally applied for every disease-related protein that acts in an oligomeric form.

Intrinsically disordered proteins
About one third of the genome encodes for intrinsically disordered proteins (IDPs) or regions in proteins. These lack stable tertiary structures and are extended, highly flexible, and composed of a large ensemble of conformations interchanging dynamically. Molecular recognition and assembly of IDRs typically involve multiple binding partners, which may result in disorder-to-order transitions. Various IDPs are involved in human diseases, making them attractive targets for drug design. Our research focuses on how intrinsic protein disorder regulates protein activity and how intrinsically disordered regions (IDRs) in proteins can be set as therapeutic targets. In many cases the C-terminal tail of a disease-related protein is disordered and has an important role in regulation. This sets disordered protein tails as particularly interesting drug targets. I will describe our studies regarding several IDRs in proteins involved in cancer and apoptosis:

1. Studying how the disordered C-terminal tailpiece of non-muscle myosin II regulates its activity by regulating its filament assembly (Ronen et al. JBC 2010, Rosenberg et al. JBC 2012 under revision)
2. How the disordered C-terminal domain of the pro-apoptotic ARTS protein regulates its activity by binding the target protein XIAP (Reingewerz et al. PLoS One 2011, Edison et al Clin Cancer Res 2012)
3. Developing peptides that bind the disordered C-terminal domain of the tumor suppressor p53 and stabilize the p53 tetramer (Gabizon et al PLoS one 2012)

Using peptide arrays to study protein interactions
Following identification of the precise interaction sites between two proteins, peptides derived from these binding sites are used either to inhibit or activate the interactions of the parent protein for therapeutic purposes. Peptide array screening is an excellent tool used to identify the precise interaction sites between the proteins and to perform structure-activity relationship studies for developing improved lead peptides. Then, structural and biophysical studies as well as studies in cells are used to validate and quantify the screening results and to test the effect of the peptides on the structure and activity of the parent protein. We apply peptide arrays to study the interactions of proteins involved in apoptosis (Katz et al, Chem Soc Rev 2011). Screening the peptide arrays is used to reveal the exact binding sites in both protein partners. Peptides derived from these binding sites are then selected as anti-cancer lead compounds for either activating or inhibiting the interactions between the full length proteins (Katz et al PNAS 2008, JBC 2012, Rotem et al JBC 2008). We also developed a method to perform structure-activity relationship studies using peptide arrays and used it for developing improved anti-HIV peptides (Gabizon et al, Med Chem Comm 2012)

Specific research topics related to Nanoscience and Nanotechnology:

• Quantitative biophysical studies of protein-protein interactions
• Using peptides to study protein-protein interactions in biological systems related to cancer and apoptosis
• Modulating protein oligomerization using peptides
• Intrinsically disordered proteins
• Peptide arrays

List of publications in Nanoscience and Nanotechnology (2011-2012)

• Friedler A. (2011) From peptides to proteins: lessons from my years at the Centre for Protein Engineering. Protein Eng Des Sel. 24(1-2):241-5.
• Noutsou M, Duarte AM, Anvarian Z, Didenko T, Minde DP, Kuper I, de Ridder I, Oikonomou C, Friedler A, Boelens R, R?diger SG, Maurice MM. (2011) Critical scaffolding regions of the tumor suppressor axin1 are natively unfolded. J Mol Biol. 405(3):773-86
• Benyamini H and Friedler A. (2011) The ASPP interaction network: electrostatic differentiation between pro- and anti-apoptotic proteins; J Mol Recognition, 24(2):266-74
• Levin A, Benyamini H, Hayouka Z, Friedler A, Loyter A. (2011) Peptides that bind the HIV-1 integrase and modulate its enzymatic activity?-?kinetic studies and mode of action. FEBS J. 278(2):316-30.
• Katz C, Levy-Beladev L, Rotem-Bamberger S, Rito T, R?diger SG, Friedler A. (2011) Studying protein-protein interactions using peptide arrays. Chem Soc Rev. 40(5):2131-45
• Sukenik S, Politi R, Ziserman L, Danino D, Friedler A, Harries D. (2011) Crowding alone cannot account for cosolute effect on amyloid aggregation. PLoS One. Jan 10;6(1):e15608.
• Flashner E, Raviv U, Friedler A. (2011) The effect of tachykinin neuropeptides on amyloid ? aggregation. Biochem Biophys Res Commun. 407(1):13-7.
• Siman P, Blatt O, Moyal T, Danieli T, Lebendiker M, Lashuel HA, Friedler A, Brik A. (2011) Chemical Synthesis and Expression of the HIV-1 Rev Protein. Chembiochem. 12(7):1097-104.
• Reingewertz TH, Shalev DE, Sukenik S, Blatt O, Rotem-Bamberger S, Lebendiker M, Larisch S, Friedler A. (2011) Mechanism of the Interaction between the Intrinsically Disordered C-Terminus of the Pro-Apoptotic ARTS Protein and the Bir3 Domain of XIAP. PLoS One. 6(9):e24655. Epub 2011 Sep 20
• Furth N, Gertman O, Shiber A, Alfassy OS, Cohen I, Rosenberg M, Kleinberger-Doron N, Friedler A, Ravid T. (2011) Exposure of Bipartite Hydrophobic Signal Triggers Nuclear Quality Control of Ndc10 at the Endoplasmic Reticulum/Nuclear Envelope. Mol Biol Cell. 22(24):4726-39
• Benyamini H., Loyter A. and Friedler A. (2011) A structural model of the HIV-1 Rev-integrase complex: the molecular basis of integrase regulation by Rev; Biochem Biophys Res Comm, 416(3-4):252-7
• Edison N, Reingewertz TH, Gottfried Y, Lev T, Zuri D, Maniv I, Carp MJ, Shalev G, Friedler A, Larisch S. (2012) Peptides mimicking the unique ARTS-XIAP binding site promote apoptotic cell death in cultured cancer cells; Clin Cancer Res. ; 18(9):2569-78
• Katz C, Zaltsman-Amir Y, Mostizky Y, Kollet N, Gross A, Friedler A. (2012) Molecular basis of the interaction between the pro apoptotic tBID protein and mitochondrial carrier homologue 2 (MTCH2): Key players in the mitochondrial death pathway.; J Biol Chem., 287(18):15016-23
• Hayouka Z., Levin A., Hurevich M., Shalev DE, Loyter A., Gilon C. and Friedler A. (2012) A Comparative Study of Backbone versus Side Chain Peptide Cyclization: Application for HIV-1 Integrase Inhibitors; Bioorg Med Chem, 20(10):3317-22
• Gabizon R, Brandt T, Sukenik S, Lahav N, Lebendiker M, Shalev DE, Veprintsev D, Friedler A. (2012) Specific Recognition of p53 Tetramers by Peptides Derived from p53 Interacting Proteins.; PLoS One. 2012;7(5):e38060.
• Maes M, Loyter A, Friedler A. (2012) Peptides that inhibit HIV-1 integrase by blocking its protein-protein interactions; FEBS J. 279(16):2795-809
• Maes M, Rimon A, Kozachkov-Magrisso L, Friedler A, Padan E.(2012) Revealing the Ligand Binding Site of NhaA Na+/H+ Antiporter and its pH Dependence; J Biol Chem., in press
• Gabizon R, Faust O, Benyamini H, Nir S, Loyter A and Friedler A (2012) Structure activity relationship studies using peptide arrays: the example of the HIV-1 Rev - Integrase interaction; Med Chem Com, in press

Significant publications:

• Hayouka Z , Rosenbluh J , Levin A , Loya S , Lebendiker M , Veprintsev DB , Kotler M , Hizi A , Loyter A and Friedler A (2007) Inhibiting HIV-1 integrase by shifting its oligomerization equilibrium; Proc Natl Acad Sci USA, 104(20):8316-21.
• Katz C. , Benyamini H. , Rotem S. , Lebendiker M. , Danieli T. , Dines, M. , Bronner, V. , Bravman, T. , Rudiger S. and Friedler A. (2008): Molecular Basis of the Interaction Between the Anti-Apoptotic Bcl-2 Family Proteins and the Pro-Apoptotic Protein ASPP2; Proc. Natl. Acad. Sci. USA, 105(34):12277-82
• Katz C, Levy-Beladev L, Rotem-Bamberger S, Rito T, R?diger SG, Friedler A. (2011) Studying protein-protein interactions using peptide arrays. Chem Soc Rev. 40(5):2131-45
• Katz C, Zaltsman-Amir Y, Mostizky Y, Kollet N, Gross A, Friedler A. (2012) Molecular basis of the interaction between the pro apoptotic tBID protein and mitochondrial carrier homologue 2 (MTCH2): Key players in the mitochondrial death pathway.; J Biol Chem., 287(18):15016-23
• Gabizon R, Brandt T, Sukenik S, Lahav N, Lebendiker M, Shalev DE, Veprintsev D, Friedler A. (2012) Specific Recognition of p53 Tetramers by Peptides Derived from p53 Interacting Proteins.; PLoS One. 2012;7(5):e38060.

Cooperation with industries and defense projects (2011-2012):

Success Stories

Cooperation with other researchers/universities in Israel:

Within Hebrew University:
Institute of chemistry: Prof. Danny Porath, Dr. Uri Raviv, Dr. Daniel Harries, Prof. Chaim Gilon, Prof. Shlomo Yitzchaik
Institute of Life Sciences: Prof. Abraham Loyter, Prof. Rachel Nechushtai, Dr. Debbie Shalev, Dr. Michal Goldberg, Prof. Etana Padan
Faculty of Medicine: Prof. Shoshana Ravid, Prof. Moshe Kotler, Dr. Ora Furman

With other universities:
Ben Gurion University: Prof. Ashraf Brik, Dr Raz Zarivach
Tel Aviv University: Prof. Nir Ben-Tal
Weizmann Institute: Prof. Atan Gross, Dr. Michal Sharon
Sheba Hospital, Tel Hashomer: Prof. Shai Izraeli

Research grants

• 2007-2011 Binational USA - Israel Science Foundation (BSF), together with Prof. Moshe Kotler, the Hebrew University, and Dr Robert Blumenthal, NCI, USA
• 07/2008-6/2013 ERC starting grant
• 2010-2012 Israel Ministry of Health
• 2012-2013 Yissum - Baby seed grant "Peptides for selective killing of HIV-1 infected cells", for 1 year together with Prof. Abraham Loyter
• 2012-2015 HUJI Nanotechnology Centre grant with Taiwan: "Using nanotechnology for developing kinase inhibitors as anti-cancer leads", together with Prof. Shlomo Yitzchaik, Prof. Danny Porath and Prof. Yu Ju Chen (Academia Sinica, Taiwan)

Students, postdocs and researchers

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