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RESEARCH INTERESTS
Complex development of flagellar biosynthesis
Flagellar biosynthesis through mutant isolation and analysis
Flagellar evolution and regulation
PUBLICATIONS
Research interests in Dr. Hughes' lab focus on genetic approaches to complex biological processes. One process so complex, creation scientists use it as an example to argue that evolution cannot be possible is the biogenesis of the bacterial flagellum. The current focus of the lab is how the genes required for assembly and function of the bacterial flagellum are regulated in response to the assembly process in Salmonella typhimurium.
We have previously shown that one critical regulatory mechanism involves a regulatory protein FlgM, which is held inside the cell prior completion of an intermediate structure, the hook-basal body. FlgM is an anti-sigma28 transcription factor. Sigma28 is a transcription factor required to transcribe genes needed late in flagellar assembly. Upon hook-basal body completion FlgM escapes from the cell and thus can no longer act as an anti-sigma28 factor. Late gene transcription ensues and flagellum synthesis is completed following the FlgM secretion checkpoint. FlgM is secreted by the flagellar Type III secretion system.
We have shown the flagellar secretion chaperones also act as transcriptional and translational regulators. The dynamics of interactions of the chaperones with their secretion substrates and the secretion of these substrates provides regulatory clocks that time the regulatory activity of the secretion chaperone with the secretion of their cognate secretion substrate. In that way specific regulatory of a given chaperone can be timed to assembly stage corresponding to its cognate substrate's secretion.
Finally, we are continuing on the recent findings that translation of some secretion substrates may be compartmentalized in the cell at the base of the flagellum. Thus, targeting for Type III secretion can occur through an mRNA secretion signal located in the 5'-untranslated region of the secretion substrate message.
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