title: A chimeric activator of transcription that uses two DNA-binding domains to make simultaneous contact with pairs of recognition sites.
abstract: Many well-known transcriptional regulatory proteins are composed of at least two independently folding domains and, typically, only one of these is a DNA-binding domain. However, some transcriptional regulators have been described that have more than one DNA-binding domain. Regulators with a single DNA-binding domain often bind co-operatively to the DNA in homotypic or heterotypic combinations, and two or more DNA-binding domains of a single regulatory protein can also bind co-operatively to suitably positioned recognition sequences. Here, we examine the behaviour of a chimeric activator of transcription with two different DNA-binding domains, that of the bacteriophage lambda cI protein and that of the Escherichia coli cyclic AMP receptor protein. We show that these two DNA-binding moieties, when present in the same molecule, can bind co-operatively to a pair of cognate recognition sites located upstream of a test promoter, thereby permitting the chimera to function as a particularly strong activator of transcription from this promoter. Our results show how such a bivalent DNA-binding protein can be used to regulate transcription differentially from promoters that bear either one or both recognition sites.
authors.affiliation: Department of Microbiology and Molecular Genetics, Harvard Medical School, 200 Longwood Avenue, Boston, MA 02115, USA.
authors.forename: R C
authors.initials: RC
authors.lastname: Langdon
authors.forename: T
authors.initials: T
authors.lastname: Burr
authors.forename: S
authors.initials: S
authors.lastname: Pagan-Westphal
authors.forename: A
authors.initials: A
authors.lastname: Hochschild
mesh_terms: D010582:Bacteriophage lambda; D001665:Binding Sites; D002373:Cyclic AMP Receptor Protein / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018983:DNA Footprinting; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism; D012321:DNA-Directed RNA Polymerases / Q000378:metabolism; D003850:Deoxyribonuclease I / Q000378:metabolism; D024202:Electrophoretic Mobility Shift Assay; D004926:Escherichia coli; D015964:Gene Expression Regulation, Bacterial; D017930:Genes, Reporter; D008957:Models, Genetic; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D020218:Response Elements / Q000235:genetics*; D015534:Trans-Activators / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic; D014764:Viral Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D002373:Cyclic AMP Receptor Protein; D004268:DNA-Binding Proteins; D011993:Recombinant Fusion Proteins; D015534:Trans-Activators; D014764:Viral Proteins; D012321:DNA-Directed RNA Polymerases; D003850:Deoxyribonuclease I