Heavy metal poisoning by elements such as mercury, lead, cadmium, and arsenic is a significant human health problem. Understanding the interaction of heavy metals with proteins is essential for defining the mechanism of toxicity, developing ways to minimize human exposure and to provide therapeutic regimens for the removal of toxic ions. Our goals are (1) to develop peptide systems that provide a foundation for understanding metal binding by metalloregulatory proteins and metallochaperones, (2) to understand the thermodynamics and kinetics of heavy metals in helical assemblies and (3) to prepare new designed peptides utilizing different ligands (e.g., histidine or D-amino acids) or asymmetric binding sites in single polypeptides that fold into 1-helical bundles. To achieve these goals we will use a de novo peptide system based on the three-stranded coiled coil peptide aggregate motif that encapsulates with high affinity single heavy metal ions and provides spectroscopic models of mercury, cadmium, and arsenic binding sites in biological systems. We will generate high resolution structures of this peptide system in the presence and absence of these heavy metals, elucidate the kinetic and thermodynamic mechanisms of heavy metal encapsulation, and expand the array of characterized systems to include single chain peptides that encapsulate heavy metals, coiled coils that provide different coordination environments than the original design and those that encapsulate more than one heavy metal ion. These studies will expand the foundation of knowledge that has been laid by the scientific community investigating metallopeptide design, metalloregulatory proteins and heavy metal detoxification. These objectives will develop insight into the interplay between metal coordination and apopeptide structure in defining the overall metallopeptide fold, an important aspect of metallopeptide design.

Public Health Relevance

Relevance to Human Health Heavy metals such as PbII, HgII, AsII and CdII cause severe health concerns due both to their acute toxicity and the long term effects of chronic exposure (e.g., the EPA estimated in 2002 that over 300,000 children in the USA had blood levels exceeding 10 ?g/dL). Our studies address these concerns in numerous ways: including making mimics of heavy metal binding sites in proteins in order to understand how heavy metals bind to proteins, defining the rates at which reactions occur and establishing the thermodynamic preferences of these metals to different sites. We are also relating this work to studies on proteins used to recognize or detoxify heavy metals in bacteria, fungi and humans (e.g., assessing how HgII interacts with the human copper chaperone HAH1).

Agency
National Institute of Health (NIH)
Institute
National Institute of Environmental Health Sciences (NIEHS)
Type
Research Project (R01)
Project #
5R01ES012236-10
Application #
8437285
Study Section
Macromolecular Structure and Function A Study Section (MSFA)
Program Officer
Balshaw, David M
Project Start
2003-06-09
Project End
2014-02-28
Budget Start
2013-03-01
Budget End
2014-02-28
Support Year
10
Fiscal Year
2013
Total Cost
$261,722
Indirect Cost
$88,832
Name
University of Michigan Ann Arbor
Department
Chemistry
Type
Schools of Arts and Sciences
DUNS #
073133571
City
Ann Arbor
State
MI
Country
United States
Zip Code
48109
Plegaria, Jefferson S; Pecoraro, Vincent L (2016) De Novo Design of Metalloproteins and Metalloenzymes in a Three-Helix Bundle. Methods Mol Biol 1414:187-96
Plegaria, Jefferson S; Herrero, Christian; Quaranta, Annamaria et al. (2016) Electron transfer activity of a de novo designed copper center in a three-helix bundle fold. Biochim Biophys Acta 1857:522-30
Tebo, Alison G; Hemmingsen, Lars; Pecoraro, Vincent L (2015) Variable primary coordination environments of Cd(II) binding to three helix bundles provide a pathway for rapid metal exchange. Metallomics 7:1555-61
Ross, Matthew R; White, Aaron M; Yu, Fangting et al. (2015) Histidine Orientation Modulates the Structure and Dynamics of a de Novo Metalloenzyme Active Site. J Am Chem Soc 137:10164-76
Plegaria, Jefferson S; Dzul, Stephen P; Zuiderweg, Erik R P et al. (2015) Apoprotein Structure and Metal Binding Characterization of a de Novo Designed Peptide, α3DIV, that Sequesters Toxic Heavy Metals. Biochemistry 54:2858-73
Mocny, Catherine S; Pecoraro, Vincent L (2015) De novo protein design as a methodology for synthetic bioinorganic chemistry. Acc Chem Res 48:2388-96
Tebo, Alison G; Pecoraro, Vincent L (2015) Artificial metalloenzymes derived from three-helix bundles. Curr Opin Chem Biol 25:65-70
Cangelosi, Virginia M; Deb, Aniruddha; Penner-Hahn, James E et al. (2014) A de novo designed metalloenzyme for the hydration of CO2. Angew Chem Int Ed Engl 53:7900-3
Zastrow, Melissa L; Pecoraro, Vincent L (2014) Designing hydrolytic zinc metalloenzymes. Biochemistry 53:957-78
Peacock, Anna F A; Pecoraro, Vincent L (2013) Natural and artificial proteins containing cadmium. Met Ions Life Sci 11:303-37

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