zrp2: a novel maize gene whose mRNA accumulates in the root cortex and mature stems (original) (raw)
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In this study, D A-protein interactions of a one kilobase region proximal to the transcription start site of the zrp2 (Zea mays root-preferential 2) gene promoter was analyzed. The intent of this research was to identify regions of the promoter and D Aprotein interactions, that are responsible for root-preferential transcription. In vitro run-on transcription assays had re ealed dramatically higher levels of transcription in 3-d-old roots than in 5-d-old leaves (Held, 1993). Interactions between regions of the zrp2 promoter and nuclear protein extracts from 3-d-old roots and 5-d-old leaves of maize were analyzed by gel mobility-shift assays. Two D A-protein complexes with each protein extract were observed with the-4 72 to-180 region of the promoter. This region showed 72% nucleotide identity with a 159 bp portion of the first intron from an a-tubulin gene that is expressed preferentially in the roots of maize (Montoliu et al., 1989). AD Aprotein complex with high electrophoretic mobility (Z2BP1) was observed with both root and leaf nuclear protein extracts. Complexes Z2BP2 and Z2BP3 were preferentially formed with root and leaf nuclear protein extracts respecti ely. ubsequently, the proteinbinding region was delimited to a 73 bp (-330 to-258) region, which contained several repeats of two sequence motifs consisting only of As and Ts. The effect of the proteinbinding sequence on transcription of the 1 kbp and the 4.7 kbp promoter fragments (fused to the GU reporter gene) were analyzed by particle bombardment-mediated transient assays in roots and lea es of maize. The transcriptional activities of promoters, with the protein-binding region deleted were compared with their respecti e intact promoters. In roots the deletion resulted in 5-fold-less transcriptional activity with the 1 kbp promoter fragment, while the 4.7 kbp promoter showed no significant decrease. In lea es no ignificant decrease was observed with either 1 kbp or 4.7 kbp promoters. We conclude that this protein-binding region is important in enhancing the le el of transcriptional acti ity in roots.
Maize Genes Specifically Expressed in the Outermost Cells of Root Cap
Plant and Cell Physiology, 1999
The cells at the periphery of the root cap are continuously sloughed off from the root into the mucilage, and are thought to be programmed to die. By using subtractive hybridization/differential screening and a transmembranedomain trapping screening strategy involving expression screening in transfected COS-7 cells, we isolated two related maize cDNAs (ZmRCPl and ZmRCP2) that are specifically expressed in the outermost one to three cells of the cap. ZmRCPl and ZmRCP2 are homologous proteins of 37 kDa mature polypeptides with a region of regularlyspaced Cys residues and putative iV-terminal signal peptides, and represent members of a novel protein family which is conserved among angiosperm and gymnosperm.
Plant Journal, 2008
The rth3 (roothairless 3) mutant is specifically affected in root hair elongation. We report here the cloning of the rth3 gene via a PCR-based strategy (amplification of insertion mutagenized sites) and demonstrate that it encodes a COBRA-like protein that displays all the structural features of a glycosylphosphatidylinositol anchor. Genes of the COBRA family are involved in various types of cell expansion and cell wall biosynthesis. The rth3 gene belongs to a monocot-specific clade of the COBRA gene family comprising two maize and two rice genes. While the rice (Oryza sativa) gene OsBC1L1 appears to be orthologous to rth3 based on sequence similarity (86% identity at the protein level) and maize/rice synteny, the maize (Zea mays L.) rth3-like gene does not appear to be a functional homolog of rth3 based on their distinct expression profiles. Massively parallel signature sequencing analysis detected rth3 expression in all analyzed tissues, but at relatively low levels, with the most abundant expression in primary roots where the root hair phenotype is manifested. In situ hybridization experiments confine rth3 expression to root hair-forming epidermal cells and lateral root primordia. Remarkably, in replicated field trials involving near-isogenic lines, the rth3 mutant conferred significant losses in grain yield.
Characterization of Polypeptides Corresponding to Clones of Maize Zein mRNAS
PLANT PHYSIOLOGY, 1987
Zeins, the storage proteins of maize (Zea mays) are a complex group of polypeptides encoded by a large multigene family. The a-zein proteins, which account for about 70% of the total, show both size and charge heterogeneity. Although clones corresponding to several different alpha zeins have been characterized, it has not been possible to correlate these sequences with individual zein polypeptides. By translating in Xenopus oocytes RNAs transcribed in vitro from cloned zein mRNAs, we were able to identify the encoded proteins among native zeins or zeins synthesized in oocytes with total zein mRNA. There was no correlation between the isoelectric points of these proteins and the homology of their oding DNA sequences, as the proteins encoded by two closely homologous cDNAs migrated with greater charge heterogeneity than those encoded by less homologous clones. In addition, the size of the proteins as determined by SDS polyacrylamide gel electrophoresis did not always correlate with the length of the protein deduced from the DNA sequence. The ability to match cloned zein sequences to individual native proteins wifl enable the genetic mapping of cloned genes as well as the analysis of their translational regulation.
A Genomic and Expression Compendium of the Expanded PEBP Gene Family from Maize
PLANT PHYSIOLOGY, 2007
The phosphatidylethanolamine-binding proteins (PEBPs) represent an ancient protein family found across the biosphere. In animals they are known to act as kinase and serine protease inhibitors controlling cell growth and differentiation. In plants the most extensively studied PEBP genes, the Arabidopsis (Arabidopsis thaliana) FLOWERING LOCUS T (FT) and TERMINAL FLOWER1 (TFL1) genes, function, respectively, as a promoter and a repressor of the floral transition. Twenty-five maize (Zea mays) genes that encode PEBP-like proteins, likely the entire gene family, were identified and named Zea mays CENTRORADIALIS (ZCN), after the first described plant PEBP gene from Antirrhinum. The maize family is expanded relative to eudicots (typically six to eight genes) and rice (Oryza sativa; 19 genes). Genomic structures, map locations, and syntenous relationships with rice were determined for 24 of the maize ZCN genes. Phylogenetic analysis assigned the maize ZCN proteins to three major subfamilies: TFL1-like (six members), MOTHER OF FT AND TFL1-like (three), and FT-like (15). Expression analysis demonstrated transcription for at least 21 ZCN genes, many with developmentally specific patterns and some having alternatively spliced transcripts. Expression patterns and protein structural analysis identified maize candidates likely having conserved gene function of TFL1. Expression patterns and interaction of the ZCN8 protein with the floral activator DLF1 in the yeast (Saccharomyces cerevisiae) two-hybrid assay strongly supports that ZCN8 plays an orthologous FT function in maize. The expression of other ZCN genes in roots, kernels, and flowers implies their involvement in diverse developmental processes.
The Maize Root Transcriptome by Serial Analysis of Gene Expression
Plant Physiology, 2005
Serial Analysis of Gene Expression was used to define number and relative abundance of transcripts in the root tip of well-watered maize seedlings (Zea mays cv FR697). In total, 161,320 tags represented a minimum of 14,850 genes, based on at least two tags detected per transcript. The root transcriptome has been sampled to an estimated copy number of approximately five transcripts per cell. An extrapolation from the data and testing of single-tag identifiers by reverse transcription-PCR indicated that the maize root transcriptome should amount to at least 22,000 expressed genes. Frequency ranged from low copy number (2–5, 68.8%) to highly abundant transcripts (100→1,200; 1%). Quantitative reverse transcription-PCR for selected transcripts indicated high correlation with tag frequency. Computational analysis compared this set with known maize transcripts and other root transcriptome models. Among the 14,850 tags, 7,010 (47%) were found for which no maize cDNA or gene model existed. C...
The EMBO journal, 1989
The structure of the zein regulatory gene Opaque 2 of Zea mays has been determined by sequence analysis of genomic and cDNA clones. The size of O2 mRNA is 1751 bp [poly(A) tail not included] containing a major open reading frame (ORF) of 1380 bp preceded by three short ORFs of 3, 21 and 20 amino acid residues. The main ORF comprises 1362 bp and is composed of six exons ranging in size from 465 to 61 bp and five introns of 678 bp to 83 bp. A putative protein 454 amino acids long was derived by the theoretical translation of the genomic sequences corresponding to exons. The opaque 2 protein contains a domain similar to the leucine zipper motif identified in DNA binding proteins of animal protooncogenes such as fos, jun and myc, and in the transcriptional activators GCN4 and C/EBP. The region of 30 amino acid residues next to the leucine repeats towards the N terminus is rich in basic amino acids and is also homologous to a domain present in fos, jun and GCN4. Moreover, in the carboxy ...
THE PLANT CELL ONLINE, 2001
We analyzed cDNA libraries from developing endosperm of the B73 maize inbred line to evaluate the expression of storage protein genes. This study showed that zeins are by far the most highly expressed genes in the endosperm, but we found an inverse relationship between the number of zein genes and the relative amount of specific mRNAs. Although ␣ -zeins are encoded by large multigene families, only a few of these genes are transcribed at high or detectable levels. In contrast, relatively small gene families encode the ␥ -and ␦ -zeins, and members of these gene families, especially the ␥ -zeins, are highly expressed. Knowledge of expressed storage protein genes allowed the development of DNA and antibody probes that distinguish between closely related gene family members. Using in situ hybridization, we found differences in the temporal and spatial expression of the ␣ -, ␥ -, and ␦ -zein gene families, which provides evidence that ␥ -zeins are synthesized throughout the endosperm before ␣ -and ␦ -zeins. This observation is consistent with earlier studies that suggested that ␥ -zeins play an important role in prolamin protein body assembly. Analysis of endosperm cDNAs also revealed several previously unidentified proteins, including a 50-kD ␥ -zein, an 18-kD ␣ -globulin, and a legumin-related protein. Immunolocalization of the 50-kD ␥ -zein showed this protein to be located at the surface of prolamin-containing protein bodies, similar to other ␥ -zeins. The 18-kD ␣ -globulin, however, is deposited in novel, vacuole-like organelles that were not described previously in maize endosperm.