title: Structure and function of the macrolide biosensor protein, MphR(A), with and without erythromycin.
abstract: The regulatory protein MphR(A) has recently seen extensive use in synthetic biological applications, such as metabolite sensing and exogenous control of gene expression. This protein negatively regulates the expression of a macrolide 2'-phosphotransferase I resistance gene (mphA) via binding to a 35-bp DNA operator upstream of the start codon and is de-repressed by the presence of erythromycin. Here, we present the refined crystal structure of the MphR(A) protein free of erythromycin and that of the MphR(A) protein with bound erythromycin at 2.00- and 1.76-A resolutions, respectively. We also studied the DNA binding properties of the protein and identified mutants of MphR(A) that are defective in gene repression and ligand binding in a cell-based reporter assay. The combination of these two structures illustrates the molecular basis of erythromycin-induced gene expression and provides a framework for additional applied uses of this protein in the isolation and engineered biosynthesis of polyketide natural products.
authors.affiliation: Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742, USA.
authors.forename: Jianting
authors.initials: J
authors.lastname: Zheng
authors.forename: Vatsala
authors.initials: V
authors.lastname: Sagar
authors.forename: Adam
authors.initials: A
authors.lastname: Smolinsky
authors.forename: Chase
authors.initials: C
authors.lastname: Bourke
authors.forename: Nicole
authors.initials: N
authors.lastname: LaRonde-LeBlanc
authors.forename: T Ashton
authors.initials: TA
authors.lastname: Cropp
mesh_terms: D001483:Base Sequence; D001665:Binding Sites; D018360:Crystallography, X-Ray; D017931:DNA Primers / Q000235:genetics; D004269:DNA, Bacterial / Q000235:genetics; D024881:Drug Resistance, Bacterial / Q000235:genetics; D004917:Erythromycin / Q000737:chemistry*; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D005798:Genes, Bacterial; D008024:Ligands; D018942:Macrolides / Q000737:chemistry*; D008958:Models, Molecular; D009154:Mutation; D011487:Protein Conformation; D055672:Static Electricity; D013816:Thermodynamics; D014157:Transcription Factors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
chemical_list: D017931:DNA Primers; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D008024:Ligands; D018942:Macrolides; C413453:MphR(A) protein, E coli; D014157:Transcription Factors; D004917:Erythromycin