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Lisa A Marcaurelle,
Eamon Comer,
Sivaraman Dandapani,
Jeremy R Duvall,
Baudouin Gerard,
Sarathy Kesavan,
Maurice D Lee,
Haibo Liu,
Jason T Lowe,
Jean-Charles Marie, [......],
Damian W Young,
Lakshmi B Akella, Nathan T Ross,
Yan-Ling Zhang,
Daniel M Fass,
Surya A Reis,
Wen-Ning Zhao,
Stephen J Haggarty,
Michelle Palmer,
Michael A Foley
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ABSTRACT: An aldol-based build/couple/pair (B/C/P) strategy was applied to generate a collection of stereochemically and skeletally diverse small molecules. In the build phase, a series of asymmetric syn- and anti-aldol reactions were performed to produce four stereoisomers of a Boc-protected γ-amino acid. In addition, both stereoisomers of O-PMB-protected alaninol were generated to provide a chiral amine coupling partner. In the couple step, eight stereoisomeric amides were synthesized by coupling the chiral acid and amine building blocks. The amides were subsequently reduced to generate the corresponding secondary amines. In the pair phase, three different reactions were employed to enable intramolecular ring-forming processes: nucleophilic aromatic substitution (S(N)Ar), Huisgen [3+2] cycloaddition, and ring-closing metathesis (RCM). Despite some stereochemical dependencies, the ring-forming reactions were optimized to proceed with good to excellent yields, providing a variety of skeletons ranging in size from 8- to 14-membered rings. Scaffolds resulting from the RCM pairing reaction were diversified on the solid phase to yield a 14 400-membered library of macrolactams. Screening of this library led to the discovery of a novel class of histone deacetylase inhibitors, which display mixed enzyme inhibition, and led to increased levels of acetylation in a primary mouse neuron culture. The development of stereo-structure/activity relationships was made possible by screening all 16 stereoisomers of the macrolactams produced through the aldol-based B/C/P strategy.
Journal of the American Chemical Society 11/2010; 132(47):16962-76. · 9.91 Impact Factor
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ABSTRACT: Artificially controlled cell recognition has potentially far-reaching applications in both the understanding and altering of biological function. The event of recognition often involves a multimeric protein binding a cellular membrane. While such an interaction is energetically favorable, it has been surprisingly underexploited in artificial control of recognition. Herein we describe how changing properties of substrate (phosphocholine, PC) self-assembly can affect both binding behavior and substrate affinity to a pentameric recognition protein (C-reactive protein, CRP). PC was modified with a short, self-assembling DNA strand to make the substrate self-assembly sensitive and responsive to ionic environment. A significant shift in CRP binding affinity was observed when substrates were assembled in the presence of Cs(+) rather than K(+). Furthermore, alteration of the linker length tethering PC to DNA showed trends similar to other multivalent systems. In optimizing these linker lengths, positive cooperativity increased and K(d) of the substrate assembly to CRP improved roughly 1000-fold. Such experiments both inform our understanding of biological, multivalent interactions in self-assembling systems and present a potential method to exogenously control events in cell recognition.
Journal of the American Chemical Society 04/2010; 132(19):6749-54. · 9.91 Impact Factor
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03/2010; , ISBN: 9780470571224
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ABSTRACT: Proteins modulate the majority of all biological functions and are primarily composed of highly organized secondary structural elements such as helices, turns and sheets. Many of these functions are affected by a small number of key protein-protein contacts, often involving one or more of these well-defined structural elements. Given the ubiquitous nature of these protein recognition domains, their mimicry by peptidic and non-peptidic scaffolds has become a major focus of contemporary research. This review examines several key advances in secondary structure mimicry over the past several years, particularly focusing upon scaffolds that show not only promising projection of functional groups, but also a proven effect in biological systems.
Philosophical Transactions of The Royal Society A Mathematical Physical and Engineering Sciences 03/2010; 368(1914):989-1008. · 2.77 Impact Factor
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ChemBioChem 04/2009; 10(5):829-33. · 3.94 Impact Factor
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ABSTRACT: The Bcl-x(L)/Bak protein-protein interaction has emerged as an important target for cancer therapy due to its role in apoptosis. Inhibition of this interaction by small-molecule antagonists induces apoptosis in unhealthy cells. Bak, a pro-apoptotic Bcl-2 protein, projects four hydrophobic side chains (V74, L78, I81, and I85), corresponding to the i, i+4, i+7, and i+11 positions of an alpha-helix, into a hydrophobic cleft on Bcl-x(L). Herein, we present a novel family of rationally designed alpha-helix mimetics with improved solubility and synthetic feasibility based on a benzoylurea scaffold. These benzoylurea derivatives favor a linear conformation stabilized by an intramolecular hydrogen bond, and are able to mimic the spatial projection of the i, i+4, and i+7 residues of an alpha-helix. The binding of the benzoylurea derivatives to Bcl-x(L) was assessed using fluorescence polarization competition assays, isothermal titration calorimetry, and (15)N-HSQC experiments. These experiments showed that these agents bind to and disrupt Bcl-x(L) with low micromolar inhibition and dissociation constants, with (15)N-HSQC experiments confirming binding to the hydrophobic pocket of Bcl-x(L) normally occupied by the Bak helix.
ChemMedChem 04/2009; 4(4):649-56. · 3.15 Impact Factor
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ABSTRACT: A supramolecular assembly containing an isoguanosine pentaplex with both a "protein-binding" face and a "reporter" face has been generated. When phosphocholine is appended to the protein-binding face this supramolecular assembly binds multivalently to the pentameric human C-reactive protein, a biomolecule implicated in inflammation and heart disease.
Journal of the American Chemical Society 03/2009; 131(14):5020-1. · 9.91 Impact Factor
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ABSTRACT: The development of small molecules that disrupt protein-protein interactions is a key goal in addressing a number of disease states. The alpha-helix is commonly found at protein interaction interfaces and has been the focus of substantial small molecule mimetic efforts. One of the primary drawbacks of many small molecule alpha-helix mimetics is their hydrophobic core structures. To address this problem we have developed a novel scaffold based on a more water soluble 5-6-5 imidazole-phenyl-thiazole core. An inhibitor of this class has been shown to disrupt the Cdc42/Dbs protein-protein interaction at micromolar concentrations and may be useful in overcoming Cdc42-induced tumor resistance to anticancer therapies.
Organic Letters 12/2008; 11(1):25-8. · 5.86 Impact Factor
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ABSTRACT: The translocated intimin receptor (TIR) of enteropathogenic and enterohemorrhagic Escherichia coli (EPEC and EHEC) is required for EPEC and EHEC infections, which cause widespread illness across the globe. TIR is translocated via a type-III secretion system into the intestinal epithelial cell membrane, where it serves as an anchor for E. coli attachment via its binding partner intimin. While many aspects of EPEC and EHEC infection are now well understood, the importance of the intermolecular contacts made between intimin and TIR have not been thoroughly investigated. Herein we report site-directed mutagenesis studies on the intimin-binding domain of EPEC TIR, and how these mutations affect TIR-intimin association, as analyzed by isothermal titration calorimetry and circular dichroism. These results show how two factors govern TIR's binding to intimin: A three-residue TIR hot spot is identified that largely mediates the interaction, and mutants that alter the beta-hairpin structure of TIR severely diminish binding affinity. In addition, peptides incorporating key TIR residues identified by mutagenesis are incapable of binding intimin. These results indicate that hot spot residues and structural orientation/preorganization are required for EPEC, and likely EHEC, TIR-intimin binding.
Protein Science 01/2008; 16(12):2677-83. · 2.80 Impact Factor
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ABSTRACT: Enteropathogenic Escherichia coli (EPEC) are Gram (-) bacteria responsible for widespread illness in the form of diarrhea. EPEC cells attach to the intestinal epithelium using a Type III secretion system common to many Gram (-) bacteria. The translocated intimin receptor (TIR) is the first protein secreted through the EPEC secretion complex, and is absolutely required for pathogenesis. It inserts into the intestinal epithelium, serving as an anchor responsible for the attachment of EPEC to the host epithelial cell. Intimin is a transmembrane protein displayed on the EPEC cell surface with an extracellular domain that binds TIR. Observation of a TIR-TIR dimer in the X-ray co-crystal structure of the extracellular domains of intimin and TIR raised the question of how these protein domains interact and function in solution. Herein we report that the extracellular domain of TIR exists in a folded and active monomeric state in solution, as confirmed by analytical ultracentrifugation, analytical size-exclusion HPLC, isothermal titration calorimetry, and surface plasmon resonance.
Biochemical and Biophysical Research Communications 12/2007; 362(4):1073-8. · 2.48 Impact Factor
