title: Interdomain linkers of homologous response regulators determine their mechanism of action.
abstract: OmpR and PhoB are response regulators that contain an N-terminal phosphorylation domain and a C-terminal DNA binding effector domain connected by a flexible interdomain linker. Phosphorylation of the N terminus results in an increase in affinity for specific DNA and the subsequent regulation of gene expression. Despite their sequence and structural similarity, OmpR and PhoB employ different mechanisms to regulate their effector domains. Phosphorylation of OmpR in the N terminus stimulates the DNA binding affinity of the C terminus, whereas phosphorylation of the PhoB N terminus relieves inhibition of the C terminus, enabling it to bind to DNA. Chimeras between OmpR and PhoB containing either interdomain linker were constructed to explore the basis of the differences in their activation mechanisms. Our results indicate that effector domain regulation by either N terminus requires its cognate interdomain linker. In addition, our findings suggest that the isolated C terminus of OmpR is not sufficient for a productive interaction with RNA polymerase.
authors.affiliation: Department of Molecular Microbiology & Immunology L220, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97201-3098, USA.
authors.forename: Don
authors.initials: D
authors.lastname: Walthers
authors.forename: Van K
authors.initials: VK
authors.lastname: Tran
authors.forename: Linda J
authors.initials: LJ
authors.lastname: Kenney
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D009097:Multienzyme Complexes / Q000378:metabolism; D010766:Phosphorylation; D011487:Protein Conformation; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D015534:Trans-Activators / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation
chemical_list: D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D009097:Multienzyme Complexes; D011993:Recombinant Fusion Proteins; D015534:Trans-Activators; C112177:osmolarity response regulator proteins; C061278:PhoB protein, Bacteria; D004247:DNA; C057843:envZ protein, E coli