Mutations that alter the kinase and phosphatase activities of the two-component sensor EnvZ.
EnvZ, a membrane receptor kinase-phosphatase, modulates porin expression in Escherichia coli in response to medium osmolarity. It shares its basic scheme of signal transduction with many other sensor-kinases, passing information from the amino-terminal, periplasmic, sensory domain via the transmembrane helices to the carboxy-terminal, cytoplasmic, catalytic domain. The native receptor can exist in two active but opposed signaling states, the OmpR kinase-dominant state (K+ P-) and the OmpR-P phosphatase-dominant state (K- P+). The balance between the two states determines the level of intracellular OmpR-P, which in turn determines the level of porin gene transcription. To study the structural requirements for these two states of EnvZ, mutational analysis was performed. Mutations that preferentially affect either the kinase or phosphatase have been identified and characterized both in vivo and in vitro. Most of these mapped to previously identified structural motifs, suggesting an important function for each of these conserved regions. In addition, we identified a novel motif that is weakly conserved among two-component sensors. Mutations that alter this motif, which is termed the X region, alter the confirmation of EnvZ and significantly reduce the phosphatase activity.
Department of Molecular Biology, Princeton University, Princeton, New Jersey 08544, USA.
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W
Hsing
F D
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Russo
K K
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Bernd
T J
TJ
Silhavy
D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics*; D029968:Escherichia coli Proteins; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes; D009154:Mutation; D010749:Phosphoprotein Phosphatases / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D017386:Sequence Homology, Amino Acid
D001425:Bacterial Outer Membrane Proteins; D029968:Escherichia coli Proteins; D009097:Multienzyme Complexes; D000255:Adenosine Triphosphate; C057843:envZ protein, E coli; D010749:Phosphoprotein Phosphatases