Functional studies on polar targeting and signaling of the PhoR protein in Escherichia coli
Abstract
A genome-wide study revealed that the PhoR histidine kinase is localized to the cell poles in Escherichia coli K-12 (WWW.ECOLIHUB.ORG/GENOBASE). Fluorescence imaging of a PhoR-Venus hybrid protein showed that the distribution of PhoR-Venus to the poles varies with the growth phase or cell cycle. During rapid growth, several patterns are observed. As cells enter the stationary phase, the fraction of cells showing polar localization dramatically increases. PhoR is inner membrane histidine kinase that is required for signal transduction in the control of the phosphate (Pho) regulon, whose expression is regulated by extracellular inorganic phosphate (Pi(ext) ). Similar patterns are seen during growth in Pi-limited and Pi excess conditions, thus suggesting that its distribution is unaffected by the Pi(ext) concentration. We further showed that the PhoR PAS domain (L107 to D193) is required for both polar localization and Pi signaling. Switching thirty-three residues lead to identifying four switches (T115A, TY153/155AA, R178A and R192A) that dramatically reduce the distribution of PhoR to the cell poles and two residues (D138 and R148) that are critical for signaling.
Degree
Ph.D.
Advisors
Wanner, Purdue University.
Subject Area
Molecular biology|Microbiology
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