Comparison of the mechanism of transmembrane signaling in bacterial chemoreceptors and sensor kinases
Year: 2006
Type: dissertation
Abstract: Membrane-bound receptors transmit information from the cell exterior to the cell interior.\nBacterial receptors capable of transmitting this information include sensor kinases, which\ncontrol gene expression via response regulators, and methyl-accepting chemotaxis proteins\n(MCPs), which control rotation of the flagellar motor. These receptors, which have a\nsimilar general architecture and function, are predicted to share similar mechanisms of\ntransmembrane signaling. The majority of such work has been conducted on MCPs. Our\ngoal is to extend this work to the closely related sensor kinases by creating functional\nhybrid transducers. I show that a chimeric protein (Nart) that joins the periplasmic, ligandbinding\ndomain of the sensor kinase NarX (nitrate/nitrite sensor) to the cytoplasmic\nsignaling domain of the chemoreceptor Tar is capable of modulating flagellar rotation in\nresponse to both nitrate and nitrite. Consistent with the properties of NarX, our Nart elicits\na stronger response to nitrate than to nitrite. Introduction of mutations into a highly\nconserved periplasmic region affects Nart signaling in a fashion that is consistent with the\neffects seen in NarX. I also present the first example of a substitution in a presumed\nligand-binding domain that confers a reverse-signal phenotype for both nitrate and nitrite in Nart. These results support the hypothesis that the key aspects of transmembrane\nsignaling are closely similar in homodimeric bacterial chemoreceptors and sensor kinases.
Author: Scott M. Ward
Language: English
Subfield: Genetics
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W2291011625