MzrA-EnvZ interactions in the periplasm influence the EnvZ/OmpR two-component regulon.
MzrA was identified as a modulator of the EnvZ/OmpR two-component signal transduction system. Previous evidence indicated that MzrA interacts with EnvZ and modulates its enzymatic activities to influence OmpR phosphate (OmpR∼P) levels. Moreover, MzrA was shown to connect the bacterial envelope stress response systems CpxA/CpxR and σ(E) to EnvZ/OmpR to widen the defensive response regulatory network. In this study, experiments were carried out to establish whether the membrane or periplasmic domain of MzrA is critical for MzrA-EnvZ interactions and to reveal MzrA residues that play an important role in these interactions. Data obtained from chimeric constructs, in which the transmembrane domain of MzrA was replaced with the unrelated transmembrane domain of NarX or signal sequence of PhoA, showed that the transmembrane domain residues of MzrA do not play a critical role in MzrA-EnvZ interactions. The importance of the periplasmic domain of MzrA in MzrA-EnvZ interactions was revealed by characterizing bifunctional, fully soluble, and periplasmically localized MalE::MzrA chimeras. This was further corroborated through the isolation of loss-of-function, single-amino-acid substitutions in the conserved periplasmic domain of MzrA that interfered with MzrA-EnvZ binding in a bacterial two-hybrid system. Together, the data suggest that the binding of MzrA to EnvZ influences the ability of EnvZ to receive and/or respond to environmental signals in the periplasm and modulate its biochemical output to OmpR.
Gerken
Henri
H
School of Life Sciences, Arizona State University, Tempe, Arizona 85287-4501, USA.
Misra
Rajeev
R
D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism*; D019943:Amino Acid Substitution / Q000235:genetics; D001425:Bacterial Outer Membrane Proteins / Q000378:metabolism*; D001426:Bacterial Proteins / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D009097:Multienzyme Complexes / Q000378:metabolism*; D016254:Mutagenesis, Insertional; D020125:Mutation, Missense; D019897:Periplasm / Q000378:metabolism*; D011485:Protein Binding; D025941:Protein Interaction Mapping; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D018085:Regulon; D017384:Sequence Deletion; D015398:Signal Transduction; D015534:Trans-Activators / Q000378:metabolism*; D020798:Two-Hybrid System Techniques
D048868:Adaptor Proteins, Signal Transducing; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D009097:Multienzyme Complexes; C554197:MzrA protein, E coli; D011994:Recombinant Proteins; D015534:Trans-Activators; C112177:osmolarity response regulator proteins; C057843:envZ protein, E coli