The goal of this proposal is to take advantage of the structural symmetry of multimeric proteins, a rarely explored property, to arrive eventually at structurally complementary multidentate protein ligands with ultra-high affinity and specificity. The long term objective is to illuminate an area of fundamental biological interest: the molecular recognition properties of multidentate protein ligands and the use of such ligands to control protein functions. Specifically, this proposal encompasses the design, synthesis and evaluation of multidentate ligands targeting a pair of ideal model systems: the heat-labile enterotoxin from E. coli (LT) and the closely related cholera toxin secreted by V. cholerae (CT), which are both AB5 heterohexamers. The biological mechanism of the actions of LT and CT includes a critical step of receptor recognition on the target cell by the B pentamer. The five-fold symmetry of the B subunits of LT and CT offers good opportunities to develop pentadentate ligands with overall structures complementary to the arrangement of toxin receptor binding sites. Such ligands will be created stepwise using a modular approach with each module providing opportunities for further optimization Building on the principles of molecular recognition, our proposed work will combine the powers of combinatorial chemistry and structure-based design to arrive at ultrahigh affinity pentadentate ligands. The affinity of the ligands obtained will be investigated with a variety of analytical tools. Detailed thermodynamics of ligand-protein interaction will be studied using a series of mono- to penta-dentate ligands. The proposed research has broad implications for the field of molecular recognition in general since it is at the frontiers of investigations focusing on multidentate ligands interacting with multimeric proteins. In addition, high affinity ligands derived from our work have potential health benefits, as they may lead to the development of agents useful for the detection, treatment, and prevention of AB5 toxin-related enterotoxigenic diseases.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
1R01AI044954-01A1
Application #
6045337
Study Section
Bio-Organic and Natural Products Chemistry Study Section (BNP)
Project Start
2000-02-01
Project End
2005-01-31
Budget Start
2000-02-01
Budget End
2001-01-31
Support Year
1
Fiscal Year
2000
Total Cost
$273,468
Indirect Cost
Name
University of Washington
Department
Anatomy/Cell Biology
Type
Schools of Medicine
DUNS #
135646524
City
Seattle
State
WA
Country
United States
Zip Code
98195
Liu, Jiyun; Begley, Darren; Mitchell, Daniel D et al. (2008) Multivalent drug design and inhibition of cholera toxin by specific and transient protein-ligand interactions. Chem Biol Drug Des 71:408-19
Liu, Jiyun; Zhang, Zhongsheng; Tan, Xiaojian et al. (2005) Protein heterodimerization through ligand-bridged multivalent pre-organization: enhancing ligand binding toward both protein targets. J Am Chem Soc 127:2044-5
Zhang, Zhongsheng; Fan, Erkang (2005) Solid-phase and solution-phase syntheses of oligomeric guanidines bearing peptide side chains. J Org Chem 70:8801-10
Zhang, Zhongsheng; Liu, Jiyun; Verlinde, Christophe L M J et al. (2004) Large cyclic peptides as cores of multivalent ligands: application to inhibitors of receptor binding by cholera toxin. J Org Chem 69:7737-40
Mitchell, Daniel D; Pickens, Jason C; Korotkov, Konstantin et al. (2004) 3,5-Substituted phenyl galactosides as leads in designing effective cholera toxin antagonists; synthesis and crystallographic studies. Bioorg Med Chem 12:907-20
Pickens, Jason C; Mitchell, Daniel D; Liu, Jiyun et al. (2004) Nonspanning bivalent ligands as improved surface receptor binding inhibitors of the cholera toxin B pentamer. Chem Biol 11:1205-15
Zhang, Zhongsheng; Pickens, Jason C; Hol, Wim G J et al. (2004) Solution- and solid-phase syntheses of guanidine-bridged, water-soluble linkers for multivalent ligand design. Org Lett 6:1377-80
Fan, Erkang; O'Neal, Claire J; Mitchell, Daniel D et al. (2004) Structural biology and structure-based inhibitor design of cholera toxin and heat-labile enterotoxin. Int J Med Microbiol 294:217-23
Zhang, Zhongsheng; Fan, Erkang (2003) Modular synthesis and study of multivalent carbohydrate ligands with long and flexible linkers. Methods Enzymol 362:209-18
Li, Jizhen; Zhang, Guangtao; Zhang, Zhongsheng et al. (2003) TFA-sensitive arylsulfonylthiourea-assisted synthesis of N,N'-substituted guanidines. J Org Chem 68:1611-4

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