Analyzing Membrane Binding Ability of FTT258

Whitney Hart Butler University
Faculty Sponsor(s): R. Jeremy Johnson Butler University
Tularemia is a deadly disease caused by the bacterium Francisella tularensis. One key protein to the virulence of this bacterium is the membrane bound serine hydrolase FTT258, a homologue of the protein human acyl protein thioesterase 1 (hAPT1). Both FTT258 and hAPT1 have key flexible beta-3 loops overhanging the active sites that move between open and closed conformations. This conformational transition is hypothesized to control the membrane binding ability of these proteins. The membrane binding ability and cellular localization of FTT258 is hypothesized to contribute to the virulence of this bacterium. A library of beta-3 loop variants of FTT258 were constructed and characterized to aid in better understanding the molecular features controlling its membrane binding ability. The membrane-binding ability of FTT258 was studied in liposomes. Kinetic data and thermal stability results were gathered for the WT protein and mutants, and the membrane binding ability of these mutant proteins was compared. Mutations to tryptophan 66 decreased the activity of the enzyme, but mutations to similar amino acids including phenylalanine, isoleucine, and leucine had lesser effects than mutations to alanine. Liposome binding revealed that the positively charged amino acids at positions 64 and 70 play key roles in the membrane binding ability of the enzyme. Further research into this protein will reveal more about the importance of the conformation of FTT258 to its membrane binding ability.
Biochemistry & Molecular Biology
Poster Presentation

When & Where

Irwin Library 3rd Floor