Genetic analysis of conserved residues in PhoU of Escherichia coli

GENETIC ANALYSIS OF CONSERVED RESIDUES IN PHOU OF ESCHERICHIA COLI Stewart G. Gardner Department of Microbiology and Molecular Biology Master of Science The Pho regulon is controlled by the PstSCAB transporter, PhoU, and the twocomponent proteins, PhoB and PhoR. PhoU is a negative regulator of the Pho regulon under phosphate-replete conditions. How PhoU functions is unknown. Many PhoU homologues are found widely throughout prokaryotic domains. There are several conserved amino acid residues in the PhoU protein. It is hypothesized that these residues play an important role in the function of PhoU. To test this hypothesis, several site directed mutations in the phoU gene have been produced with single amino acid changes in conserved residues. After testing these mutants, it was found that some of the mutants abolished repression of the Pho regulon while other mutants had little or no effect. Further study of these mutants and their phenotypes will reveal more about how PhoU functions and help to better understand bacterial signaling in general.