A maize protein associated with the G-box binding complex has homology to brain regulatory proteins.

Abstract

The G-box element is a moderately conserved component of the promoter of many inducible genes, including the alcohol dehydrogenase genes of Arabidopsis and maize. We used monoclonal antibodies generated against partially purified G-box binding factor (GBF) activity to characterize maize proteins that are part of the DNA binding complex. Antibodies interacted with partially purified maize GBF complexes to produce a slower migrating complex in the gel retardation assay. lmmunoprecipitation experiments suggested that the protein recognized by the antibody is nota DNA binding protein in and of itself, but rather is associated with the DNA binding complex. These monoclonal antibodies were used to isolate cDNA clones encoding a protein that we have designated GF14. Maize GF14 contains a region resembling a leucine zipper and acidic carboxy and amino termini, of which the latter can form an amphipathic a-helix similar to known transcriptional activators such as VP16 and GALA. Protein gel blot analysis of cell culture extract showed that a single, major protein of approximately 30 kD is recognized by anti-GFl4; the protein is also present predominantly in the kernel and root. The deduced amino acid sequence of maize GF14 is more than 80% identical to Arabidopsis GF14 and Oenothera PHP-O, and is more than 60% identical to a class of mammalian brain proteins described as both protein kinase C inhibitors and activators of tyrosine and tryptophan hydroxylases. GF14 is found in a variety of monocotyledons and dicotyledons, gymnosperms, and yeast. This suggests a deep evolutionary conservation of a potential regulatory protein associated with a core sequence found in the promoter region of many genes.

A single Arabidopsis GF14 isoform possesses biochemical characteristics of diverse 14-3-3 homologues

“…In plants, a pea 14-3-3 protein homologue inhibits PKC from sheep brain [10]. A 14-3-3 homologue is induced by inoculation of barley with Erysiphe graminis [18], and 14-3-3 homologues are associated with a DNA-binding complex in Arabidopsis and maize [6,17]. These results indicate that 14-3-3 proteins, as a family, have a very broad set of potentially important functions in cellular processes.…”

“…Members of the GF14 protein family of Arabidopsis and maize show more than 60 ~o identity with mammalian 14-3-3 proteins, are encoded by a small gene family, and are apparently associated with the G-box DNA/protein complex [6,17]. The G-box is a cis-acting DNA regulatory element that is present in promoters of many eukaryotic genes [7,17,18,21,25,33].…”

The essential yeast Tcp1 protein affects actin and microtubules.

“…Myosin binds laterally to filamentous actin (Vandekerckhove and Vancompernolle, 1992;Schroeder et al, 1993). The remaining proteins that contain this amino acid motif are the maize Zea mays protein, associated with a DNA binding complex (De Vetten et al, 1992); Prp8, an S. cerevisiae protein involved in pre-mRNA splicing (Jackson et al, 1988); the seryl-tRNA synthetase (Fujinaga et al, 1993); and the turnip yellow mosaic virus RNA replicase polyprotein (Keese et al, 1989). Hence, among all the proteins in the data bank, the Tcplp homologues, three myosin isoforms, and four other proteins, which affect nucleic acids, share this motif.…”

The an11 locus controlling flower pigmentation in petunia encodes a novel WD-repeat protein conserved in yeast, plants, and animals.

“…Total protein extracts were prepared, and protein concentration determined, as described previously (de Vetten et al 1992). For subcellular protein fraction, 20 grams of frozen corolla tissue of wild-type R27 and anl I-W134 was ground in liquid N 2 and the powder was resuspended in 40 ml of ice-cold buffer (10 mM Tris-HC1 at pH 7.5, 1 mM EDTA, 250 mM sucrose).…”