title: DNA bending by the a1 and alpha 2 homeodomain proteins from yeast.
abstract: Structural and biochemical studies of monomer homeodomain-DNA complexes have not so far revealed any cases of pronounced DNA distortion. In this paper we show that multimeric complexes of the yeast homeodomain proteins a1 and alpha 2 induced significant bends in their operators upon binding. Based on a series of circular permutation experiments, we found that a dimer of alpha 2 bound to operator DNA produced a mild bend in the DNA, whereas the alpha 2-MCM1-DNA and the a1-alpha 2-DNA complexes exhibited much sharper bends. As these latter two complexes represent the in vivo form of DNA-bound a1 and alpha 2, we conclude that, in the cell, these homeodomain proteins are associated with pronounced bends in DNA. We discuss possible roles for these bends in transcriptional repression.
authors.affiliation: Department of Microbiology and Immunology, University of California, San Francisco 94143, USA.
authors.forename: D L
authors.initials: DL
authors.lastname: Smith
authors.forename: A B
authors.initials: AB
authors.lastname: Desai
authors.forename: A D
authors.initials: AD
authors.lastname: Johnson
mesh_terms: D001483:Base Sequence; D004271:DNA, Fungal / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D005656:Fungal Proteins / Q000737:chemistry / Q000378:metabolism*; D018398:Homeodomain Proteins; D026341:Minichromosome Maintenance 1 Protein; D015778:Minor Histocompatibility Antigens; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D009875:Operator Regions, Genetic; D011487:Protein Conformation; D019253:Proto-Oncogene Proteins c-bcl-2; D051818:Replication Protein C; D012097:Repressor Proteins; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors / Q000737:chemistry / Q000378:metabolism
chemical_list: C096816:BCL2-related protein A1; D004271:DNA, Fungal; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D018398:Homeodomain Proteins; C096063:MATA1 protein, S cerevisiae; C062928:MATA2 protein, S cerevisiae; D026341:Minichromosome Maintenance 1 Protein; D015778:Minor Histocompatibility Antigens; D019253:Proto-Oncogene Proteins c-bcl-2; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D051818:Replication Protein C