title: Selective interaction of plant homeodomain proteins mediates high DNA-binding affinity.
abstract: Understanding molecular mechanisms that control cell fate in the shoot apical meristem is a fundamental question in plant development. Genetic and molecular studies demonstrate that maize KNOTTED1 (KN1) of the TALE (3-aa acid loop extension) class of homeodomain (HD) proteins is involved in shoot apical meristem function. We show that KN1 interacts with knotted interacting protein (KIP), a BEL1-like TALE HD protein. Interaction between KN1 and KIP is mediated by conserved domains in the N termini of both proteins. The KN1 DNA-binding sequence, TGACAG(G/C)T, was biochemically identified, and in vitro DNA-binding assays show that individually KN1 and the HD of KIP bind specifically to this motif with low affinity. The KN1-KIP complex, however, binds specifically to this DNA-binding motif with high affinity, indicating that the association of KN1 and KIP may function in transcriptional regulation.
authors.affiliation: Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA. harley35@uclink4.berkeley.edu
authors.forename: Harley M S
authors.initials: HM
authors.lastname: Smith
authors.forename: Ilja
authors.initials: I
authors.lastname: Boschke
authors.forename: Sarah
authors.initials: S
authors.lastname: Hake
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017343:Genes, Plant; D018398:Homeodomain Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018519:Meristem / Q000254:growth & development / Q000378:metabolism; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D020798:Two-Hybrid System Techniques; D003313:Zea mays / Q000235:genetics / Q000254:growth & development / Q000378:metabolism
chemical_list: D018744:DNA, Plant; D004268:DNA-Binding Proteins; D018398:Homeodomain Proteins; C095848:Kn1 protein, plant; D010940:Plant Proteins