title: A single amino acid substitution in the R3 domain of GLABRA1 leads to inhibition of trichome formation in Arabidopsis without affecting its interaction with GLABRA3.
abstract: GLABRA1 (GL1) is an R2R3 MYB transcription factor that regulates trichome formation in Arabidopsis by interacting with the bHLH transcription factor GLABRA3 (GL3) or ENHANCER OF GL3 (EGL3). The conserved [D/E]L×2 [R/K]×3L×6L×3R amino acid signature in the R3 domain of MYB proteins has been shown to be required for the interaction of MYBs with R/B-like bHLH transcription factors. By using genetic and molecular analyses, we show that the glabrous phenotype in the nph4-1 mutant is caused by a single nucleotide mutation in the GL1 gene, generating a Ser to Phe substitution (S92F) in the conserved [D/E]L×2[R/K]×3L×6L×3R amino acid signature of GL1. Activation of the integrated GL2p:GUS reporter gene in protoplasts by cotransfection of GL1 and GL3 or EGL3 was abolished by this GL1-S92F substitution. However, GL1-S92F interacted successfully with GL3 or EGL3 in protoplast transfection assays. Unlike VPGL1GL3, the fusion protein VPGL1-S92FGL3 failed to activate the integrated GL2p:GUS reporter gene in transfected protoplasts. These results suggested that the S92 in the conserved [D/E]L×2 [R/K]×3L×6L×3R amino acid signature of GL1 is not essential for the interaction of GL1 and GL3, but may play a role in the binding of GL1 to the promoters of its target genes.
authors.affiliation: Key Laboratory of Molecular Epigenetics of MOE and Institute of Genetics and Cytology, Northeast Normal University, Changchun, 130024, China.
authors.forename: Xuemei
authors.initials: X
authors.lastname: Dai
authors.affiliation: Key Laboratory of Molecular Epigenetics of MOE and Institute of Genetics and Cytology, Northeast Normal University, Changchun, 130024, China.
authors.forename: Limei
authors.initials: L
authors.lastname: Zhou
authors.affiliation: Key Laboratory of Molecular Epigenetics of MOE and Institute of Genetics and Cytology, Northeast Normal University, Changchun, 130024, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Molecular Epigenetics of MOE and Institute of Genetics and Cytology, Northeast Normal University, Changchun, 130024, China.
authors.forename: Ling
authors.initials: L
authors.lastname: Cai
authors.affiliation: Key Laboratory of Molecular Epigenetics of MOE and Institute of Genetics and Cytology, Northeast Normal University, Changchun, 130024, China.
authors.forename: Hongyan
authors.initials: H
authors.lastname: Guo
authors.affiliation: Key Laboratory of Molecular Epigenetics of MOE and Institute of Genetics and Cytology, Northeast Normal University, Changchun, 130024, China.
authors.forename: Hainan
authors.initials: H
authors.lastname: Tian
authors.affiliation: Department of Molecular, Cell and Developmental Biology, University of Michigan, Ann Arbor, MI, 48109, USA.
authors.forename: John
authors.initials: J
authors.lastname: Schiefelbein
authors.affiliation: Key Laboratory of Molecular Epigenetics of MOE and Institute of Genetics and Cytology, Northeast Normal University, Changchun, 130024, China.
authors.forename: Shucai
authors.initials: S
authors.lastname: Wang
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000737:chemistry* / Q000378:metabolism*; D051792:Basic Helix-Loop-Helix Proteins / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000378:metabolism*; D017343:Genes, Plant; D008954:Models, Biological; D009154:Mutation / Q000235:genetics; D010641:Phenotype; D059828:Plant Cells / Q000378:metabolism; D011485:Protein Binding; D000072417:Protein Domains; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013329:Structure-Activity Relationship; D064201:Trichomes / Q000254:growth & development* / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D051792:Basic Helix-Loop-Helix Proteins; D004268:DNA-Binding Proteins; D011993:Recombinant Fusion Proteins; C417284:GL3 protein, Arabidopsis; C071556:GL1 protein, Arabidopsis
keywords: R2R3 MYB; activator complex; bHLH protein; protein-protein interaction; transcription factor