| Charles C. Hardin
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Associate Professor
B.S., Bemidji State University, 1980 (Chemistry) Combinatorial
immunochemistry
Email:
chuck_hardin@ncsu.edu
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Changes in chromosomal DNA length at the molecular ends - the telomeres - are correlated with changes in cellular aging and cancer. Guanine-containing single-stranded termini can form novel four-stranded structures which can inhibit the recognition of telomeric DNA by telomere terminal transferase, a key RNA-containing enzyme which helps ensure that the DNA functions properly. Telomerase recognition controls chromosomal structural changes that lead to the new cell cycle, thereby regulating cellular turnover (apoptosis) and aging. When this control is breached, the number of life cycles increases, resulting in propagation of potentially mutant or metastatic cells - and cancer. Our work on the structural diversity, energetics and dynamics of G-rich sequences leads us to suspect that four-stranded DNAs might play a key role in regulating cell cycle progression and limiting cancerous cell growth. We are characterizing properties of quadruplex DNAs that could change the functional status of the strands in terms of protection, transcription, replication, legitimate and illegitimate recombination and chromosomal turnover. These studies involve in vitro analysis using spectroscopic approaches to determine structures, energies and effector-dependent interconvertability, and in vivo immunochemical approaches to determine localization and functional characteristics.
Maize
seeds produce a 32 kilodalton protein which is activated by a
specific proteolysis event to produce an enzyme which recognizes
and removes a specific nucleotide residue from ribosomal RNA,
thereby inactivating the protein synthesis apparatus. This "ribosome inactivating protein" - or RIP
- presumably recognizes the "Achilles heel" on ribosomes
of invading pests which might compete with the developing corn
plant for the foodstore in the seed. By doing so, it is thought
to mediate a natural form of pest control. Click the image on
the left for a larger picture of RIP. This project involves using
X-ray crystallography methods to determine the structure of the
protein - before and after proteolytic activation - and determining
factors which facilitate the activation and RNA-binding events.
The long-range goal is to harness and tune this novel activity
for biotechnological applications such as "magic bullet"
strategies for disease control.