Poster abstracts

Poster number 82 submitted by Emily Tillmaand

Nucleotide binding specificity of E. coli Manganese Superoxide Dismutase

Emily Tillmaand (Chemistry, John Carroll University), Lana Bengez (Chemistry, John Carroll University), Iteen Cheng (Chemistry, John Carroll University), David P. Mascotti (Chemistry, John Carroll University)

Abstract:
Bacterial manganese superoxide dismutase (MnSOD) has been shown to localize to the chromosomal portion of the cell and impart protection from ionizing radiation to DNA. The binding affinity of bacterial MnSOD to non-sequence specific double stranded oligomeric DNA has been quantitated previously by nitrocellulose filter binding and gel shift assays. In our lab, using fluorescence quenching titrations, we have found that polynucleotides bind to MnSOD in the following affinity hierarchy, poly(dU)~poly(U) > dsDNA~poly(A) > poly(C). The current study attempts to verify these observations using DNAse protection assays using 5’-biotin labeled homooligonucleotides. The composition of the oligonucleotides used was C₂₀T₂₀, T₂₀C₂₀, A₂₀C₂₀, C₂₀A₂₀, A₂₀G₂₀, and G₂₀A₂₀. Some of these assays confirmed the hierarchy found in previous studies. Some results uncovered previously unknown properties of ExoI nuclease. Contradictory results were also obtained. Further explanations of these contradictory results are being sought.

Keywords: DNAse, specificity, superoxide dismutase