Signal-dependent binding of the response regulators PhoP and PmrA to their target promoters in vivo.
Low Mg2+ promotes phosphorylation of the response regulators PhoP and PmrA and transcription of their activated genes in Salmonella enterica. Using chromatin immunoprecipitation, we have now determined that the PhoP and PmrA proteins are recruited to the regulatory region of their target genes when bacteria experience low Mg2+ but not when they are grown in high Mg2+. Even when the PhoP protein was artificially produced at 4-fold higher levels than the wild-type strain, promoter occupancy required the low Mg2+ signal. Substitution of the predicted phosphorylation site Asp-52 with a valine residue abolished phosphorylation of the PhoP protein, resulting in loss of PhoP binding to target promoters and transcription of PhoP-activated genes. Our results indicate that the promoter binding ability of the PhoP and PmrA proteins occurring in low Mg2+ is correlated with phosphorylation of these proteins in vivo.
Shin
Dongwoo
D
Department of Molecular Microbiology, Howard Hughes Medical Institute, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
Groisman
Eduardo A
EA
D001224:Aspartic Acid / Q000737:chemistry; D001426:Bacterial Proteins / Q000502:physiology*; D001665:Binding Sites; D015153:Blotting, Western; D047369:Chromatin Immunoprecipitation; D019281:Dimerization; D008274:Magnesium / Q000737:chemistry; D008957:Models, Genetic; D010766:Phosphorylation; D010957:Plasmids / Q000378:metabolism; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D019779:Salmonella enterica / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D014633:Valine / Q000737:chemistry; D001616:beta-Galactosidase / Q000378:metabolism
D001426:Bacterial Proteins; C081902:pmrA protein, Bacteria; C061064:PhoP protein, Bacteria; D001224:Aspartic Acid; D001616:beta-Galactosidase; D014633:Valine; D008274:Magnesium