title: Analysis of GT-3a identifies a distinct subgroup of trihelix DNA-binding transcription factors in Arabidopsis.
abstract: Trihelix DNA-binding factors (or GT factors) bind to GT elements found in the promoters of many plant genes. Although the binding specificity and the transcriptional activity of some members (e.g. GT-1 and GT-2) have been studied, the regulatory function of this family of transcription factors remains largely unknown. In this work, we have characterised a new GT factor, namely GT-3a, and a closely related member, GT-3b. We show that (1) they can form either homo- or heterodimers but do not interact with GT-1; (2) they are predominantly expressed in floral buds and roots; (3) GT-3a cannot bind to the binding sites of GT-1 or GT-2, but binds to the cab2 and rbcS-1A gene promoters via the 5'-GTTAC sequence, which has been previously shown to be the core of the Site 1 type of GT elements. These results suggest that GT-3a and GT-3b belong to a distinct subgroup of GT factors and that each subgroup of GT factors binds to a functionally distinct type of cis-acting GT elements.
authors.affiliation: Faculté des Sciences, Université de Picardie Jules Verne, 33 rue Saint Leu, 80039 Amiens, France.
authors.forename: Mira
authors.initials: M
authors.lastname: Ayadi
authors.forename: Virginie
authors.initials: V
authors.lastname: Delaporte
authors.forename: You-Fang
authors.initials: YF
authors.lastname: Li
authors.forename: Dao-Xiu
authors.initials: DX
authors.lastname: Zhou
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000145:classification / Q000235:genetics / Q000378:metabolism; D010802:Phylogeny; D011401:Promoter Regions, Genetic; D016415:Sequence Alignment; D014157:Transcription Factors / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D010940:Plant Proteins
chemical_list: D029681:Arabidopsis Proteins; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D014157:Transcription Factors; C484902:GT-3a protein, Arabidopsis; C077393:rice nuclear protein GT-2; D010940:Plant Proteins