Driving the expression of the Salmonella enterica sv Typhimurium flagellum using flhDC from Escherichia coli results in key regulatory and cellular differences. Issue 1 (December 2018) - Albanna, Ayman
Abstract The flagellar systems ofEscherichia coli andSalmonella enterica exhibit a significant level of genetic and functional synteny. Both systems are controlled by the flagellar specific master regulator FlhD4 C2 . Since the early days of genetic analyses of flagellar systems it has been known thatE. coli flhDC can complement a ∆flhDC mutant inS. enterica . The genomic revolution has identified how genetic changes to transcription factors and/or DNA binding sites can impact the phenotypic outcome across related species. We were therefore interested in asking: using modern tools to interrogate flagellar gene expression and assembly, what would the impact be of replacing theflhDC coding sequences inS. enterica for theE. coli genes at theflhDC S. entercia chromosomal locus? We show that even though all strains created are motile, flagellar gene expression is measurably lower whenflhDC EC are present. These changes can be attributed to the impact of FlhD4 C2 DNA recognition and the protein-protein interactions required to generate a stable FlhD4 C2 complex. Furthermore, our data suggests that inE. coli the internal flagellar FliT regulatory feedback loop has a marked difference with respect to output of the flagellar systems. We argue due diligence is required in making assumptions based on heterologous expression of regulators and that even systems showing significant synteny may not behave in exactly the same manner.