Advisor : Julie Bartley 3 : 30 pm How are mRNAs Targeted for Degradation in Cells ?

Nereis diversicolor, a marine worm, is unique in its ability to survive in high concentrations of cadmium that would be lethal to other organisms. Investigation into this characteristic led to the discovery of metalloprotein II (MPII), a member of the myohemerythrin family. The affinity of MPII for cadmium makes it unique among the myohemerythrins, which normally bind iron. MPII is thus an interesting model for investigating protein-metal coordination. MPII for study was purified from Escherichia coli containing a synthetic plasmid coding for the N. diversicolor MPII sequence. As purified, MPII contains iron, which is removed before exposing the protein to cadmium, iron, or both. The binding was measured using UV-Vis and ICP-MS. Structural changes of the protein as bound to iron or cadmium were determined through nondenaturing PAGE electrophoresis. Our data suggest that MPII binds both iron and cadmium, with higher affinity for cadmium. Results from nondenaturing PAGE suggest that MPII may have structural variation when it is bound to cadmium versus iron.