CAREER: Elucidating the molecular mechanism of the Vibrio cholerae Vc2 cyclic di-GMP riboswitch

Michigan State University, East Lansing MI

Investigators

Abstract

Intellectual Merit: A fundamental decision faced by all organisms is whether to colonize a given environment or migrate to new a one. For bacteria, this decision consists of transitioning between a motile state, and a sessile, biofilm forming existence. Biofilms are defined as multicellular communities of bacteria that are encased in a protective extracellular matrix. Biofilms are the predominant form of bacterial growth in nature, and allow bacteria to survive predation, toxic chemicals, and harsh conditions. Thus, biofilms represent important ecological niches in every environment and influence industrial applications such as agriculture, bioenergy and water purification. Over the last decade, it has become apparent that the intracellular signaling molecule cyclic di-GMP (c-di-GMP) plays a fundamental role in the vast majority of bacteria to control the transition between motility and biofilm formation. However, the molecular mechanisms by which c-di-GMP regulates these behaviors are not well understood. This research project will study a novel mechanism by which c-di-GMP exerts its function. In Vibrio cholerae, c-di-GMP binds to a conserved RNA structure called a riboswitch. Riboswitches traditionally function by controlling the expression of the downstream gene on the same RNA segment. In V. cholerae, this riboswitch is designated as Vc2. However, preliminary experiments suggest that binding of c-di-GMP to Vc2 actually increases the stability of an upstream small RNA (sRNA), which then appears to impact bacterial behaviors. This project will focus on how (a) binding of c-di-GMP to Vc2 stabilizes the traget sRNAs; (b)the Vc2 target genes are regulated; and (c) the Vc2 RNAs impacts the biology of the bacterium. This research is likely to uncover a novel genetic regulatory mechanism that governs the transitioning between distinct phases of biofilm formation. Moreover, discoveries from this project will inspire new approaches to cultivate beneficial biofilms while inhibiting harmful ones. Broader Impacts: This project will also serve as a platform to broadly engage members of the academic community and the general public in scientific education and discourse. During the period of this award, undergraduate and graduate students in an upper level microbiology course (Microbial Genetics) and in the investigator's laboratory will be taught and mentored to become highly trained members of the future scientific community. The investigator will also initiate a number of activities to further engage the general public such as the organization of an annual "Microbiology Day" at "Impression 5" science center located in Lansing, MI. The investigator will also develop and teach a continuing education program titled "Hot Topics in Sciences" as part of the Evening College curriculum at MSU. This class will provide adults from the local community with the scientific principles behind a number of controversial science topics prevalent in the public consciousness. The project team will also instruct local high-school science teachers about microbial biofilms in the MSU "Frontiers in Science" program. Finally, the research team will train underrepresented students recruited from the Summer Research Opportunities (SROP) program offered by Michigan State University.