CHARACTERIZING FLAGELLAR MOTILITY IN THE CONTEXT OF HOST-MICROBE SYMBIOSIS

About This Grant

ABSTRACT Symbiotic relationships between animals (including humans) and bacteria are ubiquitous in the natural world, and cultivating a healthy microbial community, or microbiota, is critical for the health of hosts. Our lab explores the fundamental principles of host-microbe symbiosis to learn how these relationships are formed and maintained. We focus on flagella, tail-like structures that are commonly used by bacteria to navigate their environments. Many symbiotic bacteria use flagellar motility to colonize their hosts, and the proteins that govern flagellar development and activity are critical for beneficial and pathogenic host-microbe associations. Many species from the Vibrio genus of bacteria form symbiotic relationships with animal hosts, ranging from invertebrate mutualists like Vibrio fischeri to human pathogens like Vibrio cholerae. In symbiotic Vibrios, flagellar motility is critical for the establishment of the host-microbe relationship, and mutations in the flagellar apparatus reduce both their general motility and their ability to colonize their hosts. Although flagellar motility is well-described in some bacteria in vitro, the genetic requirements for flagellar function and specific types of motility are often restricted to artificial conditions that do not reflect real world conditions. Further, we and others have found that in vitro characterizations of flagellar motility in simple environments do not generalize to the motility behaviors that bacteria use inside the bodies of their host organisms. Over the next five years, we will use the model symbiosis between the Hawaiian bobtail squid and Vibrio fischeri to characterize the role of flagellin proteins, which make up the flagellar filament, in symbiotic motility. We will determine the role of individual flagellins and flagellin diversity in motility, then will measure how flagellins shape motility in complex, host-like environments. Finally, we will assay the role flagellins play in symbiotic colonization. This work will uncover new information about the structure and function of bacterial flagella, and will further characterize how bacteria use motility to colonize and impact their hosts.