February 24, 2015, 4:00 PM, HSB T-639
Christoph Grundner, Ph.D.
Assistant Professor, Seattle Biomedical Research Institute
Affiliate Assistant Professor, Department of Global Health
University of Washington
"Surprises in Mycobacterium tuberculosis Phosphosignaling"
Phosphosignaling in Mycobacterium tuberculosis reinforces the idea that protein phosphorylation on serine and threonine is central not only to eukaryotic, but also to bacterial signaling. We identified new components and a new branch of Mycobacterium tuberculosis phosphosignaling, protein tyrosine phosphorylation. These findings extend the similarities with eukaryotic phosphorylation systems but also suggest distinct differences between pro- and eukaryotic phosphosignaling and highlight the limitations of viewing bacterial phosphosignaling within the confines of the 'eukaryotic-like' model.
March 3, 2015, 4:00 PM, HSB T-639
Arash Komeili, Ph.D.
Associate Professor of Microbiology
Department of Plant and Microbial Biology
University of California, Berkeley
"Exploring the mechanisms of compartmentalization and biomineralization in diverse microorganisms"
Bacteria display a dazzling degree of architectural complexity at the subcellular level including the presence of lipid-enclosed structures that superficially resemble eukaryotic organelles. The study of bacterial organelles promises to answer fundamental mechanistic questions regarding the organization of the bacterial cytoplasmic space and the evolution of eukaryotic endomembrane system. In addition, the unique activities of bacterial organelles are a source of inspiration for novel biomedical and industrial applications. The magnetosome organelles of magnetotactic bacteria (MB) represent an ideal system for basic and applied approaches to understand and exploit bacterial compartments. MB are ubiquitous in aquatic environments and possess the remarkable ability to align in and navigate along geomagnetic field lines, a strategy that streamlines their search for low oxygen environments. This behavior is mediated by the magnetosome organelle, a lipid-enclosed compartment that houses a 50 nanometer-sized crystal of the iron oxide magnetite (Fe3O4) or the iron sulfide greigite (Fe3S4). Individual magnetosomes are organized into one or more chains that are fixed to the cell body and thus passively align the organism with external magnetic fields. By establishing model systems amenable to molecular and genetic manipulation, my group has been able to identify specific sets of genes that act at each step of the magnetosome formation process. We are now studying the functions of these factors in detail and developing platforms to uncover novel compartmentalization and biomineralization genes amongst diverse MB. In addition, we are actively engaged in developing applications that take advantage of the magnetic properties of magnetosomes.