Melisa Cherney

Assistant Professor - Biochemistry
Department of Chemistry and Biochemistry
University of Northern Iowa
Cedar Falls, IA 50614-0423

Office: 262 McCollum Science Hall
Voice: 319-273-2557
Fax: 319-273-7127
E-mail: Melisa.Cherney@uni.edu

Degrees

  • B.S.- University of Minnesota-Duluth, 2000
  • Ph.D. - University of Wisconsin-Madison, 2007

Research Interests

  • Bioinorganic methods of protein regulation
  • Spectroscopic correlation between protein structure and function

The appropriate regulation of protein function in response to environmental factors is essential to all known life and is accomplished through a wide variety of methods.  While some of these regulatory mechanisms are well understood, there are many which are poorly understood or undiscovered.   Regulation generally occurs via some induced change in the protein structure, either by covalent modification of the protein molecule (e.g, amide bond cleavage, phosphorylation, ubiquitination) or by changes in the overall protein fold.  In metalloproteins the overall protein structure can also be controlled by which amino acid side chains serve as ligands to a bound metal ion.

The focus of the Cherney lab is on understanding how some proteins are regulated by ligand exchange reactions when the cysteine(thiolate) ligand to the heme is displaced by another ligand, particularly when the heme is reduced from the Fe3+ to the Fe2+ state.  This emerging class of heme proteins can respond to physiological indicators such as the presence of carbon monoxide or nitric oxide, or the redox potential of the cell.  The proteins in this class also have a diverse set of functions, ranging from transcriptional activators to ion channels to kinases.  Since many of these proteins are large and unstable (some even contain transmembrane domains), our lab generates variants of cytochrome c by site-directed mutagenesis and uses them as a model system.  Studying the cysteine(thiolate) ligand switch in this controlled system allows us to manipulate and study the individual molecular interactions to determine how the heme active site is tuned to respond to only the correct physiological effector in different protein systems.
 
Structure of the heme macrocycle in the Fe2+ state (left) and the structure of the Met80→Cys variant of cytrochrome c, as predicted by the SwissPDB Viewer program (right).

Illustration of the cysteine(thiolate) heme ligand switch mechanism in the protein CooA (found in the bacterium Rhodospirillum rubrum).  Carbon monoxide binding in the final step transforms the protein into a transcriptional activator and allows the bacterium to live on CO as its sole energy and carbon source.

 

Department of Chemistry and Biochemistry
University of Northern Iowa
1227 West 27th Street
Cedar Falls, IA 50614-0423
Phone: 319-273-2437
FAX: 319-273-7127
E-mail: barbara.reid@uni.edu
Web: http://www.chem.uni.edu

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