Assistant Professor

Biology

University of Massachusetts, Boston (Boston, MA)

I examine the molecular requirements for chronic intracellular colonization by Sinorhizobium meliloti during its nitrogen-fixing symbiosis with legume hosts.

My lab is interested in addressing the question of how a cell monitors its environment and then uses this information to implement physiological adaptation. In particular, I examine bacterial cell cycle progression and its modification in response to a variety of internal and external cues. As a model system, I study the Gram-negative bacterium Sinorhizobium meliloti, which establishes a nitrogen-fixing symbiosis within the roots of leguminous plants such as alfalfa. S. meliloti gain entry to host tissues, are endocytosed, and then establish a persistent infection within the host cell cytoplasm where they differentiate into a morphologically distinct “bacteroid” form capable of nitrogen fixation.

One remarkable aspect of bacteroid differentiation is a filamentous cell morphology that is accompanied by several rounds of genomic endoreduplication. This is a particularly striking observation given that S. meliloti appears to strictly limit the initiation of DNA replication to once per cell cycle during free-living growth. Thus, the host is able to impinge upon cycle progression during intracellular bacteriod growth. My lab is interested in determining the molecular events that underlie the choice bacterial cells make during exit from S-phase as they transition into either G2-phase (during free-living growth), back to G1-phase (during bacteroid endoreduplication) or into G0-phase as they finally exit the cell cycle during terminal bacteroid differentiation. In S. meliloti, very little is known regarding the molecular components that carry out cell cycle progression or how the process is regulated. My lab is using genetics, cell biology and biochemistry approaches to characterize a two-component signal transduction network that impinges on cell cycle regulation.

2005 Teaching Assistant, Cold Spring Harbor Protein Purification Course

2004 Student, Cold Spring Harbor Protein Purification Course

2002-2005 National Science Foundation Postdoctoral Fellow