title: Operator binding by lambda repressor heterodimers with one or two N-terminal arms.
abstract: The first 6 amino acids (NH2-Ser1-Thr2-Lys3-Lys4-Lys5-Pro6) of bacteriophage lambda cI repressor form a flexible arm that wraps around the operator DNA. Homodimeric lambda repressor has two arms. To determine whether both arms are necessary or only one arm is sufficient for operator binding, we constructed heterodimeric repressors with two, one, or no arms by fusing the DNA binding domain of lambda repressor to leucine zippers from Fos and Jun. Although only one arm is visible in the cocrystal structure of the N-domain-operator complex, our results indicate that both arms are required for optimal operator binding and normal site discrimination.
authors.affiliation: Department of Biochemistry and Biophysics, Texas A&M University, College Station 77843-2128, USA.
authors.forename: Y I
authors.initials: YI
authors.lastname: Kim
authors.forename: J C
authors.initials: JC
authors.lastname: Hu
mesh_terms: D000595:Amino Acid Sequence; D010582:Bacteriophage lambda / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D001665:Binding Sites; D004279:DNA, Viral / Q000235:genetics; D004268:DNA-Binding Proteins; D016350:Leucine Zippers / Q000235:genetics; D008969:Molecular Sequence Data; D009875:Operator Regions, Genetic / Q000235:genetics; D011487:Protein Conformation; D016760:Proto-Oncogene Proteins c-fos / Q000235:genetics; D016755:Proto-Oncogene Proteins c-jun / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D014764:Viral Proteins; D054334:Viral Regulatory and Accessory Proteins
chemical_list: D004279:DNA, Viral; D004268:DNA-Binding Proteins; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D014764:Viral Proteins; D054334:Viral Regulatory and Accessory Proteins; C016649:phage repressor proteins