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2002
LSU-HHMI Summer Undergraduate Research Program |
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 Kristy
I. Roper, Jacob E. Dowden, (Grover L. Waldrop, LSU Dept. of
Biological Sciences) Targeting Acetyl-CoA Carboxylase
Using Bacteriophage Display
Acetyl-CoA carboxylase catalyzes the first committed step in
the biosynthesis of long-chain fatty acids. The Escherichia
coli form of the enzyme consists of biotin carboxylase, carboxyltransferase,
and a biotin carboxyl carrier protein. The biotin carboxyl carrier
protein has the biotin moiety covalently attached and acts as
a substrate for biotin carboxylase and carboxyltransferase.
Thus the catalytic mechanism involves protein-protein interactions.
The objective of this research is to find peptide ligands that
interrupt these interactions. Bacteriophage display was used
to identify possible peptide ligands for biotin carboxylase
and carboxyltransferase. Phage display allows for rapid selection
of peptide ligands, from a large pool of random sequences, for
specific target molecules by an in vitro technique biopanning.
Biopanning was done by incubating a library of phage-displayed
peptides with a plate coated with carboxyltransferase or biotin
carboxylase, the unbound phage was washed away. The bound phage
was amplified and the DNA was sequenced to determine the peptide
sequence. For biotin carboxylase the consensus sequence was
X-Met-Met-Met-X-X-Met. The consensus sequence for carboxyltransferase
was Ser-Thr-Met-Arg-Met-Met-X. The fact that both consensus
sequences contained several Met residues was consistent with
the strictly conserved sequence found in biotin carboxyl carrier
protein which is Ala-Met-Lys-Met. Future work will involve synthesizing
these peptides to determine their inhibitory activity.
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