Dr. Eric Stabb – Professor and Head Department of Biological Sciences Eric graduated from the University of Wisconsin-Madison in 1990 with a B.S. and majors in Molecular Biology and Philosophy. As an undergraduate, he studied molecular genetics and cytochrome maturation in Rhodobacter sphaeroidesunder the guidance of Timothy Donohue. He stayed at UW for graduate school, joining Jo Handelsman’s lab and earning his Ph.D. in Bacteriology in 1997. His graduate research focused on zwittermicin A and the plant-associated Bacillus cereusstrains that produce it. He then moved to the University of Hawaii to study the V. fischeri-E. scolopessymbiosis with Ned Ruby, initiating the research system that he took with him upon joining the faculty at the University of Georgia in 2001. In 2019, he joined the Biological Sciences Department at the University of Illinois at Chicago.
Contact Info: [email protected] Department Head office: SES 3240 Lab Office: MBRB 4202
Kathryn (Katie) Bellissimo – PhD Candidate and Visiting Research Specialist
Katie graduated with a B.S. in Biology from The College of New Jersey in 2017. She then joined the Stabb Lab at The University of Georgia in Fall 2017, pursuing a PhD in Microbiology. Katie moved to Chicago with the Stabb Lab in January 2020 and continues her work in the lab as a Visiting Research Specialist at UIC. She achieved PhD candidacy in June 2019 and remains a PhD candidate at UGA long-distance from Chicago.
Katie’s Project: Bioluminescence in Vibrio fischeri is regulated by two structurally and functionally different pheromone-signaling (PS) systems: LuxI/LuxR and AinS/AinR. LuxI and AinS produce the pheromone molecules N-3-oxo-hexanoyl homoserine lactone (3OC6-HSL) and N-octanoyl-L-homoserine lactone (C8-HSL), respectively. 3OC6-HSL and C8-HSL can each bind to LuxR, stimulating formation of a multimeric LuxR-HSL complex that activates transcription of the bioluminescence operon. Though PS systems homologous to LuxI/LuxR and AinS/AinR are common among Proteobacteria, V. fischeriis unusual in that it contains two structurally dissimilar homoserine lactone (HSL) systems to control the same phenotype. Interestingly, LuxR has diverged rapidly between V. fischeristrains, but it is unclear how the resulting LuxR variants differ in their abilities to process information from HSL signals. We analyzed the sequences of twenty-three artificially and naturally evolved luxR variants and generated V. fischeri strains with fourteen of those luxRvariants under constitutive expression disconnected from PS feedback regulation. Using models of LuxR activity and computational analysis to assess the fit of our data to the models, we are probing how different LuxR variants are affected in their response to defined combinations of 3OC6- and C8-HSLs. Our results suggest how LuxR activity is influenced by different pheromones and how the rapid evolution of LuxR is related to processing information from two distinct signals. Contact info: [email protected] MBRB Room 4210
Macey Coppinger - PhD candidate and Visiting Research Specialist Macey graduated from the University of Illinois in 2017 with a Bachelor’s degree in Molecular and Cellular Biology. She started graduate school that fall at the University of Georgia, pursuing a doctorate in microbiology. She has worked under Eric’s direction since November 2017.
Macey’s Project: Bacterial peptidoglycan (PG) is an important component of the cell wall, providing structural support and protection from environmental stresses, while still allowing for cellular growth and division. PG structure is highly conserved, but there are examples of natural variation. Understanding the mechanisms of, and the constraints on, such PG variation will inform our understanding of antibiotic resistance, innate immunity, and the evolution of bacteria and pages. We are interested in PG structure in Vibrio fischeri, because of PG’s role in the model symbiosis between V. fischeriand the Hawaiian bobtail squid. Specifically, PG monomers released from V. fischeri triggers normal host development of the symbiotic organ. In this study, we altered V. fischeri’s PG biosynthesis by generating auxotrophic mutants in normal PG biosynthesis that require external sources of peptidoglycan-specific amino acids, then selecting suppressor mutants able to overcome this auxotrophy. Experiments with a D-glutamate auxotroph led to characterization of two groups of suppressors: some with mutations in a glutamate/Na+ symporter, and one mutant that generated a fusion protein involving a broad-spectrum racemase. Symporter mutants may use other amino acids in the medium to build wild-type PG. The fusion-protein mutant appears to produce both wild-type PG and PG with a novel peptide sequence. These data broaden our understanding of D-amino acids, and the evolution of PG structure. Contact info: [email protected] MBRB Room 4210