Research Interests
My laboratory studies development in simple organisms that are accessible to genetic manipulation. The organisms we study are unicellular bacteria Shewanella oneidensis and Bacillus subtilis. S. oneidensis MR-1 is a motile, facultative γ-Proteobacterium with remarkable respiratory versatility; it can utilize a range of organic and inorganic compounds as terminal electron acceptors for anaerobic metabolism. Shewanellae are recognized free-living microorganisms and members of microbial communities involved in the decomposition of organic matter and the cycling of elements in aquatic and sedimentary systems. To function and compete in environments that are subject to spatial and temporal environmental change, Shewanella must be able to sense and respond to such changes and therefore require relatively robust sensing and regulation systems. The overall goal of this project is to apply the tools of genomics, leveraging the availability of genome sequence for 18 additional strains of Shewanella, to better understand the ecophysiology and speciation of respiratory-versatile members of this important genus. To understand these systems we propose to use genome-based approaches to investigate Shewanella as a system of integrated networks; first describing key cellular subsystems – those involved in signal transduction, regulation, and metabolism - then building towards understanding the function of whole cells and, eventually, cells within populations. As a general approach, this project will employ complimentary “top-down” – bioinformatics-based genome functional predictions, high-throughput expression analyses, and functional genomics approaches to uncover key genes as well as metabolic and regulatory networks. The “bottom-up” component employs more traditional approaches including genetics, physiology and biochemistry to test or verify predictions.
B. subtilis undergo elaborate cycles of cellular differentiation that culminate in the formation of a dormant cell, the spore. In B. subtilis this differentiation cycle involves the transformation of a vegetative cell into a two-compartment sporangium within which the spore is produced. The two compartments receive identical chromosomes yet have dissimilar developmental fates involving differential expression of distinct sets of genes. We have demonstrated that the E2 subunit of pyruvate dehydrogenase complex was essential to the bacterial sporation. However, the enzymatic activity of the complex per se was not required for the biological process. We further revealed that the protein functions as a regulator in sporation. Thereby, we are interested in understanding how this protein regulates the process and what its target genes would be.