PvAlf, an embryo‐specific acidic transcriptional activator enhances gene expression from phaseolin and phytohemagglutinin promoters

• Published in: The Plant journal : for cell and molecular biology Vol. 8; no. 3; pp. 331 - 343
• Main Authors: Bobb, Andrew J., Eiben, Hans Georg, Bustos, Mauricio M.
• Format: Journal Article
• Language: English
• Published: Osney Mead, Oxford OX2 0EL, UK Blackwell Science Ltd 01.09.1995; Blackwell Science
• Subjects: Amino Acid Sequence; Arabidopsis - genetics; Base Sequence; Biological and medical sciences; Cotyledon; DNA Primers; Fabaceae - genetics; Fabaceae - metabolism; Fundamental and applied biological sciences. Psychology; Gene Expression; Gene Expression Regulation, Plant; Genes, Plant; Metabolism; Molecular and cellular biology; Molecular genetics; Molecular Sequence Data; Nitrogen metabolism; Phaseolus vulgaris; Phytohemagglutinins - biosynthesis; Phytohemagglutinins - genetics; Plant Lectins; Plant physiology and development; Plant Proteins; Plants, Medicinal; Polymerase Chain Reaction; Promoter Regions, Genetic; Replication; Restriction Mapping; RNA, Messenger - metabolism; Sequence Homology, Amino Acid; TATA Box; Toxins, Biological - metabolism; Trans-Activators - biosynthesis; Trans-Activators - genetics; Trans-Activators - metabolism; Zea mays - genetics; Storage protein; Phaseolin; Homology; Stimulation; Phytohemagglutinin; Gene expression; Promoter; Grain legume; Leguminosae; Phaseolus vulgaris; Dicotyledones; Angiospermae; N terminal-Sequence; Spermatophyta; Transcription factor
• ISSN: 0960-7412; 1365-313X
• DOI: 10.1046/j.1365-313X.1995.08030331.x

Mutations in Vp1 and ABI3 genes of maize and Arabidopsis lead to drastic reductions in the synthesis of a subset of maturation‐specific products including seed storage proteins. Gene Phaseolus vulgarisABI3‐like factor (PvAlf), whose protein product is similar to the ABI3 and Vp1 proteins, has been cloned. Here, it is shown that PvAlf positively regulates phaseolin and phytohemagglutinin (PHA‐L) promoters in particle bombardment assays. PvAlf mRNA expression is embryo‐specific and temporally complex. PvAlf mRNA abundance is highest during two periods (9–14 and 22–35 days after flowering) that precede the onsets of seed maturation and seed abscission, respectively. Protein fusions with the DNA‐binding domain of the yeast transcriptional activator GAL4 demonstrated that the N‐terminal 243 amino acids of PvAlf function as a strong transcriptional activation domain in yeast (Saccharomyces cerevisiae) and plant cells. This domain consists of a central cluster rich in serine, threonine and proline (STP cluster) flanked by two negatively charged regions containing bulky hydrophobic residues similar to acidic activation domains of Vp1, the herpes simplex virus virion protein VP16 and transcription factors GCN4 and HAP4 from yeast. Together with the Vp1 proteins of maize and rice and ABI3, PvAlf constitutes a class (Vp1/ABI3‐like factors or VAlfs) of regulatory factors that are pivotal for the promotion of seed maturation and dormancy in angiosperms.