Disease relevance of GBF1

• To study the phosphorylation of one of the G-box binding factors from Arabidopsis (GBF1), we have obtained large amounts of this protein by expression in Escherichia coli [1].
• The Mx8 imm gene, required for superinfection immunity, has a sequence similar to that of Arabidopsis thaliana G-box-binding factor 1 [2].

High impact information on GBF1

• GBF1 and GBF2 mRNA is present in light and dark grown leaves as well as in roots [3].
• Furthermore, we demonstrate that GBF1, GBF2 and GBF3 heterodimerize and these heterodimers also interact with the G-box, suggesting a potential mechanism for generating additional diversity from these GBF proteins [3].
• Here we demonstrate using the random binding site selection method that GBF1 interacts with, in addition to the palindromic G-box, other DNA motifs that fall into seven distinct groups [4].
• The N-terminal domain of GBF1 is defined by a high proline content [4].
• We demonstrate that this N-terminal proline-rich domain of GBF1, when fused to a heterologous DNA binding domain, stimulates transcription in both plant protoplasts and mammalian cells [4].

Biological context of GBF1

• In an effort to identify potential GBF binding and control partners, maize GBF1 was used as bait in a yeast two-hybrid screen of an A. thaliana cDNA library [5].
• Phosphorylation of GBF1 resulted in stimulation of the G-box binding activity and formation of a slower migrating protein-DNA complex [1].
• The N-terminal one-third of HBP-1a(17), termed the P region (residues 1-118) due to its Pro content, did not activate the reporter gene, in contrast to the corresponding Pro-rich region of Arabidopsis GBF1 (residues 1-110), which functions as an activation domain [6].
• Two other conserved sequences, showing a lesser degree of evolutionary conservation, are found upstream of the G box but do not bind to the G box binding factor (GBF) [7].
• Reduction of G-box binding factor DNA binding activity, but not G-box binding factor abundance, causes the downregulation of RBCS2 expression during early tomato fruit development [8].

Anatomical context of GBF1

• To study individual GBFs, DNA constructs fusing GBF1, GBF2 and GBF4 to GUS were made and assayed by transient expression in SB-M protoplasts [9].

Associations of GBF1 with chemical compounds

• A basic leucine zipper transcription factor, G-box-binding factor 1, regulates blue light-mediated photomorphogenic growth in Arabidopsis [10].

Physical interactions of GBF1

• GPRI2 interacted with the Pro-rich region of GBF1 [11].
• COP1 physically interacts with GBF1 and is required for the optimum accumulation of GBF1 protein in light-grown seedlings [12].

Regulatory relationships of GBF1

• DNA binding activity of the Arabidopsis G-box binding factor GBF1 is stimulated by phosphorylation by casein kinase II from broccoli [1].

Other interactions of GBF1

• Homodimers of the three proteins specifically recognize the G-box motif, with GBF1 and GBF3 binding symmetrically to this palindromic sequence [3].
• A fourth member of the Arabidopsis G-box-binding factor (GBF) family of bZIP proteins, GBF4, has been isolated and characterized [13].
• We show that although both TGA1 and GBF1 bind to the Hex motif (TGACGTGG), this binding can be distinguished on the basis of their specific DNA-protein contacts [14].
• Reconstitution of Arabidopsis casein kinase II from recombinant subunits and phosphorylation of transcription factor GBF1 [15].

Analytical, diagnostic and therapeutic context of GBF1

• DNA affinity chromatography demonstrated that each protein detected with anti-GBF1 specifically bound the G-box [9].
• Immunoblot analysis of nuclear and cytoplasmic fractions from Arabidopsis and soybean (SB-M) cell cultures indicated that over 90% of proteins detected with anti-GBF1 were cytoplasmic [9].
• Antibodies interacted with partially purified maize GBF complexes to produce a slower migrating complex in the gel retardation assay [16].

References