NSF Postdoctoral Fellowship in Biology FY 2020:Consequences of reductive evolution on cell wall metabolism in the obligate intracellular bacterium Rickettsia parkeri

Figueroa-Cuilan, Wanda Melissa, Towson MD

Investigators

Abstract

This action funds an NSF Postdoctoral Research Fellowship in Biology for FY 2020, Broadening Participation of Groups Under-represented in Biology. The fellowship supports a research and training plan for the Fellow that will increase the participation of groups underrepresented in biology. Bacteria are single-celled microbes that have evolved to colonize a wide variety of natural environments including soil, lakes, and even the depths of the ocean. Some bacteria have evolved to become dependent on hosts, forming beneficial (endosymbiotic) or detrimental (pathogenic) associations. The Rickettsiales are bacteria that grow exclusively inside a host cell and may be transmitted to mammals by ticks and other arthropods. Through evolution, the Rickettsiales have lost many genes that support essential activities, leading to their strict dependence on the host for growth. While the understanding of processes that allow growth of free-living organisms is well-developed, knowledge of these processes in bacteria that live within host cells is limited due to a lack of tools. Through this award, the fellow will translate technologies available for free-living organisms to understand how bacteria residing inside host cells grow and replicate, focusing on a member of the Rickettsiales. The project has the potential to impact insect biology and to provide novel bacterial or host targets for the next generation of antimicrobial drugs. In addition, the project will develop a graduate student and postdoctoral trainee mentoring program, called BRIDGE, to enhance diversity by maximizing graduate student advancement and retention. Using Rickettsia parkeri as a representative member of the Rickettsiales, the objectives of this project are (1) to implement live and fixed microscopy methods for quantitatively evaluating growth of single bacterial cells within the host cell and (2) to characterize R. parkeri slow-growing mutants. To address these objectives, the fellow will develop live time-lapse and fixed microscopy with probes for active cell wall synthesis coupled to quantitative image analysis tools. This approach will establish methods for quantifying parameters of growth in intracellular bacteria. Second, the fellow will characterize intracellular growth and cell wall metabolism of slow-growing mutants in the cell wall recycling pathway factor AmpG. During execution of this project, the fellow will receive training by the sponsor scientist and a postdoctoral advisory committee, and will leverage resources available at the Professional Development and Career Office at Johns Hopkins University. Finally, the fellow will broaden the participation of underrepresented groups by creating a mentoring program called BRIDGE. The core of the program involves matching URM postdocs as mentors to graduate students from diversity and inclusion-oriented organizations at Johns Hopkins University to help graduate students develop and meet their individual development plan goals while advancing postdoctoral training. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.