James Dunn's Graduate Defense Seminar

A Graduate Defense Seminar will be presented by James Dunn, MS candidate in Environmental Microbiology. He will present Evolution and Functional Analysis of Hematite Binding Peptides in 370 Kottman Hall.

Microorganisms interact with and grow on a variety of surfaces in the environment. Understanding how microbes use their protein machinery to attach to surfaces can help us prevent infection, maintain infrastructure, and even advance technologies for producing alternative energy. This study utilized short peptides to explore how amino acid sequence influences affinity for the iron-oxide mineral hematite (α-Fe₂O₃). Phage display technology was used to screen more than three billion random peptides for their specific affinity for hematite. Molecular dynamics simulations and atomic force microscopy were used to compare single-molecule dissociation constants and kinetic off-rates of two peptides that displayed affinity for hematite. Analysis of these data suggest that substituting the amino acid serine with threonine may increase a peptide’s affinity for hematite. These findings have potential to improve existing microbial fuel cell technology. Further, this study provides a unique glimpse into the forces of natural selection that may have played a role in the evolution of mineral-reducing bacteria as we know them today.

Brian Lower, advisor