Department of Chemistry

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Structure of Mammalian Mitochondrial mRNAs

Mitochondria play a crucial role in the metabolism of mammalian cells. Through the process of oxidative phosphorylation, mitochondria generate about 90% of the energy used in the cells of higher organisms. Human mitochondrial DNA makes messenger RNAs (mRNAs) for 13 proteins, all of which are required for the generation of energy. The mechanism by which the specialized mitochondrial protein biosynthetic apparatus locates start codons and initiates translation of these mRNAs is currently unknown. In a collaborative project between the Weeks and Spremulli laboratories, the structures of the start sites for all mRNAs in mitochondria were determined. The structural determinations were carried out by the application of SHAPE chemistry which queries the flexibility of an RNA with single nucleotide resolution.

The data obtained are consistent with a model in which the specialized mitochondrial ribosome preferentially allows passage of unstructured 5' sequences into the mRNA entrance site to participate in translation initiation. This information represents the first time that all RNAs in a single transcriptome have been characterized and is crucial for understanding the expression of the genetic information contained within mitochondria.

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Macromolecular Crowding & Protein Dynamics

The inside of living cells is crowded, and the consequences of crowding are expected to be profound, but surprisingly few studies are conducted under crowded conditions. In a recent JACS Communication (130, 6310-6311), the Pielak laboratory reports on the dynamical response of an ordered protein and a disordered protein to macromolecular crowding. They show that the ordered protein is more sensitive to the crowded environment than is the disordered protein. The findings provide insight about the inherent properties of disordered proteins, which are often associated with neurodegenerative diseases, and suggest that it may be more difficult to obtain information about ordered proteins from in-cell NMR data.

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Crystal Structure of Gold Nanoparticle

As published recently in JACS, the Murray Group reports the crystal structure of the thiolate gold nanoparticle [TOA⁺][Au₂₅(SCH₂CH₂Ph)_18^-], where TOA⁺ = N(C8H17)4⁺. The crystal structure reveals three types of gold atoms: (a) one central gold atom whose coordination number is 12 (12 bonds to gold atoms); (b) 12 gold atoms that form the vertices of an icosahedron around the central atom, whose coordination number is 6 (five bonds to gold atoms and one to a sulfur atom), and (c) 12 gold atoms that are stellated on 12 of the 20 faces of the Au₁₃ icosahedron.

The arrangement of the latter gold atoms may be influenced by aurophilic bonding. Together they form six orthogonal semirings, or staples, of -Au₂(SCH₂CH₂Ph)_3^- in an octahedral arrangement around the Au₁₃ core.

DeSimone Awarded Lemelson-MIT Prize

The interface between seemingly disparate fields and concepts offers the best opportunity for invention and innovation, according to UNC Chemistry professor Joseph M. DeSimone. A well-recognized chemist and polymer expert, DeSimone has uniquely applied his skills to the development of groundbreaking solutions in green manufacturing, and promising applications in gene therapy and drug delivery, as well as medical devices. For his pioneering inventions, lab-to-marketplace entrepreneurship and commitment to mentorship, DeSimone has been awarded this year’s $500,000 Lemelson-MIT Prize.

“DeSimone has established a stellar record of achievement and innovation,” said Dr. Robert S. Langer, Institute Professor at the Massachusetts Institute of Technology, who nominated DeSimone for the Lemelson-MIT Prize. “Joe is clearly one of the most inventive researchers in all of science.”

DeSimone, Chancellor’s Eminent Professor of Chemistry at the University of North Carolina at Chapel Hill and William R. Kenan, Jr. Distinguished Professor of Chemical Engineering at North Carolina State University, will accept his award and present his accomplishments to the public at the Massachusetts Institute of Technology during the second-annual EurekaFest, a multi-day celebration of the inventive spirit, June 25-28, presented by the Lemelson-MIT Program.

To view a short video profile of Joseph DeSimone and listen to podcasts of him talking about his work, follow THIS LINK

Papoian Named Dreyfus Teacher-Scholar

Garegin Papoian, Ph.D., an assistant professor in the Department of Chemistry, has been named a 2008 Camille Dreyfus Teacher-Scholar, a national recognition for research and teaching given to outstanding young faculty in the chemical sciences. This $75,000 award was created in 1946 to promote the chemical sciences.

Papoian uses advanced computational methods to study biophysical processes at multiple scales, including protein dynamics, chromatin folding and regulation of cell motility. Packaging of genetic materials in cells of higher organisms is accomplished using chromatin, the complex of DNA and protein found inside the nuclei of cells. Cell motility processes allow cells to move around in the body, for example, to move to a wound site and aid in repair.

Churchill Scholarship

Stephanie Jones has received a 2008–09 Churchill Scholarship, valued at $46,000 to $52,000, for graduate work at Cambridge University in England.

Stephanie, a chemistry major with a minor in entrepreneurship, will seek a master’s degree in chemistry in England, aiming at becoming a university research professor. Stephanie is one of 13 Churchill Scholars chosen nationwide by the Winston Churchill Foundation of the United States. Carolina is the only North Carolina institution with Churchill Scholars this year. Since 1993, 12 UNC students have received the Churchill.

Functional Anatomy of Phospholipid Binding

As recently reported in Molecular Cell by the Redinbo Group in collaboration with the Bankaitis group at UNC, Sec14, the major yeast phosphatidylinositol (PtdIns)/ phosphatidylcholine (PtdCho) transfer protein, regulates essential interfaces between lipid metabolism and membrane trafficking from the trans-Golgi network (TGN). How Sec14 does so remains unclear. They report that Sec14 binds PtdIns and PtdCho at distinct, but overlapping, sites, and both PtdIns and PtdCho-binding activities are essential Sec14 activities.

Department of Chemistry
Campus Box 3290
Caudill and Kenan Laboratories
The University of North Carolina at Chapel Hill
Chapel Hill, NC 27599-3290 USA
Phone: (919) 843-7100