Craig D Ellermeier Ph.D.

Associate Professor
Eckstein Medical Research Building
Lab phone: 
540 M
Research Focus: 

Work in the Ellermeier Lab focuses on how Gram-positive bacteria sense and respond to extracellular signals. Our work is focused on the opportunistic human pathogen Clostridium difficile and the model organism Bacillus subtilis.  We are interested in understanding how cells respond to changes in their environment by altering gene expression. To alter gene expression bacteria must detect changes in their environment and then transduce that signal from outside the cell to a transcriptional response inside the cell. We are interested in understanding the basic molecular mechanisms involved in how cells sense and respond to extracellular signals. We utilize genetic, molecular, biochemical and structural approaches to dissect these signal transduction systems.

We are particularly interested in understanding the response of C. difficile to factors produced by the innate immune system. Our work has revealed the presence of an Extra Cytoplasmic Function (ECF) σ factor, σV, present in C. difficile and B. subtilis as well as other Gram-positive bacteria that is activated specifically by lysozyme, an essential component of the innate immune system. We have found that σV is required for lysozyme resistance in both B. subtilis and C. difficile. The activity of σV is inhibited by the anti-sigma factor RsiV. Activation of σV occurs via proteolytic destruction of an anti-sigma factor RsiV. This degradation occurs only in the presence of lysozyme and requires multiple proteases to destroy RsiV in a process of regulated intramembrane proteolysis (RIP). We are interested in identifying the proteases required for σV activation and understanding the mechanism by which site-1 cleavage of RsiV, and thus σV activation, is controlled. We are also studying the role of additional ECF sigma factors encoded by C. difficile to determine their role in response to cell envelope stress. In addition, we are interested in understanding the role of these ECF sigma factors play in survival of the bacterium during an infection.


Research Mode: 
Research Paradigm(s): 
Gene-environment Interactions and Interplay
Protein Folding and Structure
Protein-protein Interactions
Transcription and Transcriptional Regulation
Translation and Post-translational Modifications
Microbiome and Infectious Diseases
Microbial and Viral
Carver College of Medicine

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