Discipline: Biological Sciences
Courtney E. Sims - Tougaloo College
Co-Author(s): Mary E. Marquart, University of Mississippi Medical Center, Jackson, MS
Bacterial toxins are often secreted proteins with specific enzyme activity that adversely affect host cells. Others can form pores in host cell membranes by binding host membrane components and inducing conformational changes that ultimately lead to cell lysis. Streptococcus pneumoniae is one of the more common bacterial pathogens that cause ocular infections, and this bacterium produces a protein toxin that forms pores in the cell membranes of ocular tissues. A human clinical endophthalmitis isolate, E335, was cultured to stationary phase in vitro and cellfree extracts of the extracellular milieu containing secreted bacterial products were concentrated 100-fold. The concentrated sample was then applied to a Sephacryl S300 gel filtration column to fractionate bacterial proteins. The fractionated proteins were then used to perform assays to determine cytotoxicity and protease activity of the isolate. Fractionated samples 6 through 30 produced more than 50% cytotoxicity of retinal pigmented epithelial (RPE) cells relative to control. Fractions 17-26 were found to have the highest protease activity relative to that of the trypsin (positive control). Further isolation of protein bands will aid in identifying a toxin and/or protease.
Funder Acknowledgement(s): Jackson Heart Study
Faculty Advisor: Mary E. Marquart,