Research Abstract 

​

The Allosteric Regulation of Caenorhabditis elegans Acyl-CoA Oxidase by ATP

The nematode C. elegans secretes ascarosides, a class of pheromones
worms use to communicate with each other. The ascarosides consist of
an ascarylose core structure and a fatty acid-derived side chain. The
side chains of the ascarosides are shortened by peroxisomal β-
oxidation cycles. Acyl-CoA oxidase is involved in the rate limiting step
of β-oxidation and installs a double bond at the α-β position of the
ascaroside-CoA. Previously, the crystal structure of C. elegans Acyl-CoA
Oxidase 1.1 (ACOX-1.1) revealed the purified enzyme was bound not
only to its FAD cofactor but also to ATP. Prior kinetic studies show that
ACOX incubated without ATP or FAD gradually lost its activity. This loss
could be blocked by the addition of ATP and FAD, but not FAD alone.
We hypothesize that ATP functions as an allosteric regulator and that
the binding of the enzyme to ATP alters the enzyme conformation and
affects the affinity between the enzyme and its FAD cofactor. We will
study the immediate effect of ATP and/or FAD addition on the activity
of ACOX-1.1 using an HRP-coupled kinetic assay. To study the key
residues involved in the allosteric network, we will utilize mutagenesis
and assay the kinetics of the mutant enzyme.