title: Genetic analysis of GalR tetramerization in DNA looping during repressosome assembly.
abstract: The Gal repressosome is a nucleoprotein complex consisting of 2 GalR dimers, 1 HU, and 1 DNA loop, which represses the transcription of the gal operon. We have adopted a structure-based genetic approach to complement ongoing physical studies of the complex. Homology-based and subsequent alanine-scanning mutageneses suggest that five residues in the DNA-distal subdomain of GalR dimer are important for repressosome formation. A further analysis of these and intragenic suppressors of looping-defective GalR mutants as well as gain-of-function mutants that permit repressosome assembly in the absence of HU show that GalR dimers contact each other in the repressosome in a partially stacked configuration.
authors.affiliation: Laboratory of Molecular Biology, NCI, National Institutes of Health, Bethesda, Maryland 20892-4264, USA.
authors.forename: Mark
authors.initials: M
authors.lastname: Geanacopoulos
authors.forename: Sankar
authors.initials: S
authors.lastname: Adhya
mesh_terms: D000409:Alanine / Q000737:chemistry; D000483:Alleles; D004247:DNA / Q000737:chemistry; D019281:Dimerization; D004926:Escherichia coli / Q000378:metabolism; D029968:Escherichia coli Proteins; D008957:Models, Genetic; D008958:Models, Molecular; D016296:Mutagenesis; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D009690:Nucleic Acid Conformation; D010957:Plasmids / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011487:Protein Conformation; D012097:Repressor Proteins / Q000737:chemistry*; D014158:Transcription, Genetic
chemical_list: D029968:Escherichia coli Proteins; C050993:Galactose repressor proteins; D012097:Repressor Proteins; D004247:DNA; D000409:Alanine