title: Arabidopsis GARP transcriptional activators interact with the Pro-rich activation domain shared by G-box-binding bZIP factors.
abstract: The Pro-rich regions, found in a subset of plant bZIP transcription factors, including G-box-binding factors (GBFs) of Arabidopsis thaliana, are thought to be deeply involved in transcriptional regulation. However, the molecular mechanisms of the Pro-rich region-mediated transcriptional regulation are still largely unknown. Here we report evidence showing that two closely related Arabidopsis proteins, designated GPRI1 and GPRI2, containing a GARP DNA-binding domain, are likely partners of one or more GBFs. The results of yeast two-hybrid assays and in vitro binding assays indicated that GPRI1 can interact with the Pro-rich regions of GBF1 and GBF3. GPRI2 interacted with the Pro-rich region of GBF1. GPRI1 and GPRI2 transactivated transcription in yeast. In GPRI1 the region responsible for this activation was mapped in the N-terminal third of the protein. Transient assays showed that in Arabidopsis cells not only the N-terminal but also the C-terminal regions of GPRI1 can function as a separable activation domain. GPRI1 and GPRI2 may function in some promoters in concert with a GBF through interaction with its Pro-rich region to enhance the transcriptional level of the corresponding genes.
authors.affiliation: Department of Botany, Graduate School of Science, Kyoto University, Kyoto, 606-8502 Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Tamai
authors.forename: Masaki
authors.initials: M
authors.lastname: Iwabuchi
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Meshi
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D050976:Basic-Leucine Zipper Transcription Factors; D018076:DNA, Complementary / Q000235:genetics / Q000302:isolation & purification; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D051790:G-Box Binding Factors; D008969:Molecular Sequence Data; D011485:Protein Binding; D025941:Protein Interaction Mapping; D017386:Sequence Homology, Amino Acid; D015534:Trans-Activators / Q000235:genetics* / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic; D020798:Two-Hybrid System Techniques
chemical_list: D029681:Arabidopsis Proteins; D050976:Basic-Leucine Zipper Transcription Factors; D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D051790:G-Box Binding Factors; D015534:Trans-Activators; D014157:Transcription Factors; C456845:GPRI1 protein, Arabidopsis; C468868:GLK2 protein, Arabidopsis