title: Direct observation of a 91 bp LacI-mediated, negatively supercoiled DNA loop by atomic force microscope.
abstract: Escherichia coli lactose repressor (LacI), a tetrameric protein, is a paradigmatic transcriptional factor that controls the expression of lacZYA in the lac operon. It specifically binds to the O1, O2, and O3 operators of the lac promoter, forms DNA loops, and regulates transcription of the lac operon. In this article, utilizing combined techniques of DNA-nicking assay and AFM imaging, we directly observed a 91 bp LacI-mediated, negatively supercoiled DNA loop mimicking the DNA loop between the O1 and O3 operators in the lac promoter.
authors.affiliation: Biomolecular Sciences Institute, Florida International University, Miami, FL, USA.|Department of Chemistry & Biochemistry, Florida International University, Miami, FL, USA.
authors.forename: Geraldine
authors.initials: G
authors.lastname: Fulcrand
authors.affiliation: Biomolecular Sciences Institute, Florida International University, Miami, FL, USA.|Department of Physics, Florida International University, Miami, FL, USA.
authors.forename: Prem
authors.initials: P
authors.lastname: Chapagain
authors.affiliation: Department of Physics, Emory University, Atlanta, GA, USA.
authors.forename: David
authors.initials: D
authors.lastname: Dunlap
authors.affiliation: Biomolecular Sciences Institute, Florida International University, Miami, FL, USA.|Department of Chemistry & Biochemistry, Florida International University, Miami, FL, USA.
authors.forename: Fenfei
authors.initials: F
authors.lastname: Leng
mesh_terms: D004278:DNA, Superhelical / Q000737:chemistry*; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000378:metabolism*; D056968:Lac Repressors / Q000737:chemistry / Q000378:metabolism*; D018625:Microscopy, Atomic Force; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D011487:Protein Conformation
chemical_list: D004278:DNA, Superhelical; D029968:Escherichia coli Proteins; D056968:Lac Repressors; C539064:LacI protein, E coli
keywords: DNA loop; atomic force microscope; the lac operon; the lac promoter; the lac repressor