Bacillus subtilis & Clostridium difficile

Kieran Pechter
Predoctoral Student
B.A. Wellesley College, 2004

Thesis Topic
Genetic and physiological analysis of the role of aconitase in gene regulation

Current Research
My thesis project focuses on aconitase, an Fe-S cluster protein in Bacillus subtilis. Many aconitases are bifunctional: they act as enzymes or RNA-binding proteins, depending on the state of the Fe-S cluster. In the presence of the cluster, aconitase (Acn) is an enzyme; however, apo-Acn binds to stem-loop structures found in the untranslated (UTR) regions of mRNA. B. subtilis Acn is bifunctional; it binds to RNA in vitro. We have established that this RNA-binding function of Acn is essential for the proper progression of sporulation. Mutations in B. subtilis Acn that target putative RNA-binding residues result in a delay in the formation of heat-resistant spores. In addition, we have discovered one sporulation transcript that is a target of aconitase, gerE. My project has focused on two major questions: What elements of the gerE mRNA are necessary and sufficient for the interaction with Acn? Does Acn have other sporulation-specific targets? My studies so far have focused on putative stem-loop structures in the gerE 3' UTR; we hypothesize that aconitase binds to a stem-loop. By looking at other potential targets of aconitase, we hope to elaborate a consensus sequence and structure for aconitase binding.

Publications

1. Serio AW, Pechter KB, Sonenshein AL. Bacillus subtilis aconitase is required for efficient late-sporulation gene expression. J Bacteriol. 2006 Sep;188(17):6396-405. Erratum in: J Bacteriol. 2007 Jul;189(14):5403.