Beneficial microbes are essential for the overall health of eukaryotic organisms, including humans. To explore the fundamental principles underlying chronic infections of host epithelial tissue by beneficial microbes, I have been studying the mutualistic symbiosis between the marine bacterium Vibrio fischeri and the Hawaiian squid Euprymna scolopes. In particular, I have focused on characterizing the LuxU-LuxO signaling system of V. fischeri, which is conserved in all members of the Vibrionaceae, including pathogens such as V. cholerae and V. vulnificus. While this signaling system regulates virulence factors in pathogenic vibrios, my current research shows that LuxU-LuxO signaling is also important for V. fischeri to establish the symbiosis with squid. Recently, I have discovered that multiple sensor proteins interact with the LuxU-LuxO regulatory pathway, suggesting that a complex signaling network controls the expression of genes involved in bacterial colonization. Here, I propose to examine this form of signaling crosstalk as it functions in nature. Specifically, I plan to systematically characterize the interactions between LuxU and the sensor proteins using both genetic and biochemical approaches. I will also identify which sensor proteins are active in the host and determine their corresponding regulons. Finally, I will determine whether signaling by the LuxU-LuxO system has an impact on host mucus secretion, which terminates after V. fischeri successfully colonizes the squid. This K99 award will enable me to complete my postdoctoral training under the mentorships of Drs. Edward Ruby and Margaret McFall-Ngai, so I may launch a comprehensive interdisciplinary research program to study host-microbe interactions as an independent investigator at a major research institution.

Public Health Relevance

Bacteria must integrate multiple signaling inputs to coordinate responses appropriate to their environments. Examining cell signaling in a beneficial microbe within its natural host niche will uncover the fundamental principles of host-microbe interactions and contribute to our understanding of the roles microbes have on our health.

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
Career Transition Award (K99)
Project #
Application #
Study Section
Special Emphasis Panel (ZGM1-BRT-9 (KR))
Program Officer
Flicker, Paula F
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
University of Wisconsin Madison
Schools of Medicine
United States
Zip Code
Koch, Eric J; Miyashiro, Tim; McFall-Ngai, Margaret J et al. (2014) Features governing symbiont persistence in the squid-vibrio association. Mol Ecol 23:1624-34
Cao, Xiaodan; Studer, Sarah V; Wassarman, Karen et al. (2012) The novel sigma factor-like regulator RpoQ controls luminescence, chitinase activity, and motility in Vibrio fischeri. MBio 3:
Miyashiro, Tim; Ruby, Edward G (2012) Shedding light on bioluminescence regulation in Vibrio fischeri. Mol Microbiol 84:795-806
Miyashiro, Tim; Klein, Will; Oehlert, Dane et al. (2011) The N-acetyl-D-glucosamine repressor NagC of Vibrio fischeri facilitates colonization of Euprymna scolopes. Mol Microbiol 82:894-903