Andrew Krieg
IUUR STEM Summer Research Program
Major: Biology
Mentors: Blake Peterson and Julia van Kessel
Vibrio campbellii is a gram-negative aquatic bacterium that causes vibriosis in many marine animals, including shrimp. It is part of the Vibrio genus which also contains Vibrio cholerae, a highly studied pathogenic bacteria that infects humans. The flagella, the cellular machine responsible for motility in bacteria, have been linked to the ability to colonize and infect organisms in vibrios. There are several genes responsible for flagellar proteins, and these genes are controlled by regulatory proteins including FlrA, FlrC, sigma-28 and sigma-54 organized into a hierarchy with checkpoints. Because the flagellum is so complex and contains regulatory checkpoints, flagellar synthesis is an important mechanism for studying cellular development in bacteria. Although the flagellar gene hierarchy has been studied in V. cholerae and other bacteria, V. campbellii appears to have a different hierarchy. In V. cholerae, there is a proposed four-tier hierarchy in which FlrA and FlrC are responsible for different classes, but in V. campbellii there appears to be a three-tier hierarchy in which FlrA and FlrC may be able to regulate the same genes. In mutants where flrC was deleted, random mutations in flrA restored motility, so we recreated these isolated mutations in several different strain backgrounds in order to test their effects with motility assays and reporter assays using plasmid reporters we designed.
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