M. Elizabeth Stroupe | Homepage

Assistant Professor of Biological Science

Research Intrests:

What is the relationship between a molecule's structure and its activity in the cell? I am interested in understanding the structure-function relationships driving two pathways: mRNA metabolism and sulfur metabolism. I use x-ray crystallography and single-particle cryogenic electron microscopy (cryo-EM) to probe across resolutions, so that I can link atomic-resolution details, macromolecular assemblies, and cellular activity.

As a precursor messenger RNA (mRNA) is transcribed, it is also processed. A 5' cap is added, noncoding regions are excised, and a polyadenylate tail is added. Together, the processed mRNA and its protein complement make up the messenger ribonucleoprotein particle (mRNP), which determines what happens to that transcript. In some cases, it is translated immediately upon nuclear export. In others, misspliced RNAs are degraded. Sometimes, the message is silenced, and the mRNA is localized before the protein is translated. The mRNP's structure is unknown, so we do not understand the relationship between that structure and its evolution through the cell. I am developing new approaches to determining the structures of these challenging molecules.

Bacteria and plants can reduce inorganic sulfur for incorporation into organic molecules; higher eukaryotes, like human beings, cannot. One step along this sulfur-assimilation pathway, the six-electron reduction of sulfite to sulfide, is performed by an enzyme called sulfite reductase, which consists of a reductase that binds flavin cofactors (called sulfite reductase flavoprotein) and a hemoprotein that binds iron-rich cofactors (called the sulfite reductase hemoprotein). We know the atomic-resolution structure of each component but not how they fit together to move six electrons from solution to the substrate. Using a combination of x-ray crystallography and cryo-EM, I am dissecting the molecular interactions important for this chemical reaction.

Recent Publications:

Stroupe, M. E., C. Xu, B. J. Goode, and N. Grigorieff. 2009. Actin filament labels for localizing protein components in large complexes viewed by electron microscopy. RNA 15:244-248.
Sache, C., J. Z. Chen, P. D. Coureux, M. E. Stroupe, M. Färich, and N. Grigorieff. 2007. High-resoluion electron microscopy of helical specimens: a fresh look at tobacco mosaic virus. Journal of Molecular Biology 3:812-835.
Stroupe, M. E., T. Ø Tange, D. R. Thomas, M. J. Moore, and N. Grigorieff. 2006. The three dimensional architecture of the EJC core. Journal of Molecular Biology 4:743-749.