SummaryThe Arabidopsis mutants fus3 and abi3 show pleiotropic effects during embryogenesis including reduced levels of transcripts encoding embryo-speci®c seed proteins. To investigate the interaction between the B3-domain-containing transcription factors FUS3 and ABI3 with the RY cis-motif, conserved in many seed-speci®c promoters, a promoter analysis as well as band-shift experiments were performed. The analysis of promoter mutants revealed the structural requirements for the function of the RY ciselement. It is shown that both the nucleotide sequence and the alternation of purin and pyrimidin nucleotides (RY character) are essential for the activity of the motif. Further, it was shown that FUS3 and ABI3 can act independently of each other in controlling promoter activity and that the RY cis-motif is a target for both transcription factors. For FUS3, which is so far the smallest known member of the B3-domain family, a physical interaction with the RY motif was established. The functional and biochemical data demonstrate that the regulators FUS3 and ABI3 are essential components of a regulatory network acting in concert through the RY-promoter element to control gene expression during late embryogenesis and seed development.
SummaryThe Arabidopsis thaliana mutants fus3, lec1 and abi3 have pleiotropic defects during late embryogenesis. Mutant embryos fail to enter the maturation programme and initiate a vegetative germination pathway instead. Screening for genes which are differentially expressed in the fus3 mutant of Arabidopsis resulted in the isolation of several members of the MYB family. MYB domain proteins in plants represent an extended gene family of transcription factors, suggesting their participation in a variety of plant specific cellular functions. Here, the authors describe one of these genes, designated AtMYB13, representing a novel member of the MYB gene family. The structure of the gene as well as its genomic organisation and localisation are reported. The expression of the gene is regulated by dehydration, exogenous abscisic acid, light and wounding. A chimeric AtMYB13 promoter/GUS gene is tissuespecifically expressed in transgenic Arabidopsis plants. The GUS staining was predominantly detected in the shoot apex zone and at the basis of developing flowers. In addition, the AtMYB13 gene promoter is active at branching points of the inflorescence. Furthermore, ectopic expression of the AtMYB13 gene has a characteristic impact on the architecture of the inflorescence leading to peculiar hook structures at pedicel branching points. In addition, some transgenic plants exhibit a reversed order of first flowers and axillary buds. These data suggest a function of the AtMYB13 gene product in linking shoot morphogenic activity with environmental as well as intrinsic signals.
Chromosomal high-mobility-group (HMG) proteins occur ubiquitously in eukaryotes and their common structural and biochemical features indicate a critical role. In this context, we compared structural and functional aspects of HMG proteins from the monocotyledonous plant maize and the dicotyledonous plant Vicia faba. Besides biochemical similarities and immunological differences found between these proteins, the isolation and characterization of a cDNA encoding the V. faba homologue of the maize HMGa protein revealed great similarities between these two proteins, including the HMG-box DNA-binding motif and an acidic domain. Therefore, like the maize HMGa protein, the V. faba HMG protein belongs to the vertebrate HMG1 family, which consists of HMG proteins and transcription factors of various eukaryotes.
To study the molecular structure and function of pyruvate decarboxylase (PDC) from plants the protein was isolated from pea seeds and partially characterised. The active enzyme which occurs in the form of higher oligomers consists of two different subunits appearing in SDSiPAGE and mass spectroscopy experiments. For further experiments, like X-ray crystallography, it was necessary to elucidate the protein sequence.Partial cDNA clones encoding pyruvate decarboxylase from seeds of Pisum sativum cv. Miko have been obtained by means of polymerase chain reaction techniques. The first sequences were found using degenerate oligonucleotide primers designated according to conserved amino acid sequences of known pyruvate decarboxylases. The missing parts of one cDNA were amplified applying the 3'-and 5'-rapid amplification of cDNA ends systems. The amino acid sequence deduced from the entire cDNA sequence displays strong similarity to pyruvate decarboxylases from other organisms, especially from plants. A molecular mass of 64 kDa was calculated for this protein correlating with estimations for the smaller subunit of the oligomeric enzyme. The PCR experiments led to at least three different clones representing the middle part of the PDC cDNA indicating the existence of three isozymes. Two of these isoforms could be confirmed on the protein level by sequencing tryptic peptides. Only anaerobically treated roots showed a positive signal for PDC mRNA in Northern analysis although the cDNA from imbibed seeds was successfully used for PCR.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.