Key Departmental News
Nucleosome Core Particle Structure Featured on Journal Cover. Researchers at the Oak
Ridge National Laboratory (ORNL) have just reported a high-resolution structure of the
nucleosome core particle (NCP). This work provides a foundation for further studies of the
structure of the nucleosome itself, the structure of different DNA sequences, the effects of DNA
damage on chromatin structure, molecular interactions that occur during genetic expression, and
the biochemical basis of inherited diseases such as Rett Syndrome. The nucleosome is a complex
of biological macromolecules that has a key role in DNA packaging and regulation of gene
expression and DNA replication in the nucleus of cells. The structure is published in the
December 2000 issue of Acta Crystallographica Section D (Biological Crystallography), the
journal of the International Union of Crystallography, and is featured on the cover of the journal.
The ORNL researchers first developed computational techniques to identify a specific DNA
sequence that produced highly homogeneous reconstituted nucleosome core particles. The
nucleosome core particles that resulted facilitated the growth of crystals that could diffract to
high resolution. After preparation and purification of the complexes, crystals were grown in
microgravity on a National Aeronautics and Space Administration (NASA) shuttle mission. The
crystals were then analyzed by x-ray crystallography at the National Synchrotron Light Source at
Brookhaven National Laboratory. Data were obtained that enabled construction of a structural
model with resolution of 2.5 Å, allowing the positioning of more than 150 amino acids of the
functionally important protein tails that were previously unobserved. The model shows how the
NCP interacts with DNA and how this fundamental building block of the chromosome binds
with dimethyl arsenate, an environmental toxin and potential carcinogen.
Contact: Roland Hirsch, SC-73, 3-9009
BER Researchers Selected for DOE Energy 100 Bright Light Award for a Biomechanical
Pancreas. Researchers at Lawrence Livermore National Laboratory (LLNL) were the recent
recipients of the prestigious DOE Energy 100 Bright Light Award for their research on the
development of a Biomechanical Pancreas. An estimated 16 million Americans suffer from
diabetes in the U.S. alone, where diabetes is the third leading cause of death by disease. Current
methods of measuring blood glucose levels, often involving a finger stick, are painful,
inconvenient, and prone to error. Additionally, it is virtually impossible to test frequently enough
with current technologies to maintain relatively stable glucose levels. The biomechanical
pancreas developed by Livermore, uses an innovative fluorescent chemical sensor to accurately
monitor the glucose levels in the blood in real-time. The insulin pump is composed of a small
battery-operated pump with an insulin reservoir and a computer chip that allows the user to
control insulin delivery. The complete system is fully implantable in the body and thus, able to
measure glucose levels continuously. This eliminates the need for diabetics to self-administer
numerous daily insulin injections. LLNL has recently teamed with MiniMed, Inc., to further
develop the chemical glucose sensor for biomechanical pancreas.
Contact: Dean Cole, SC-73, 3-3268