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PvAlf, an embryo‐specific acidic transcriptional activator enhances gene expression from phaseolin and phytohemagglutinin promoters
Author(s) -
Bobb Andrew J.,
Eiben Hans Georg,
Bustos Mauricio M.
Publication year - 1995
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1046/j.1365-313x.1995.08030331.x
Subject(s) - promoter , activator (genetics) , embryo , gene , microbiology and biotechnology , gene expression , biology , genetics
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 P haseolus v ulgaris A BI3‐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 ( V p1/ A BI3‐ l ike f actors or VAlfs) of regulatory factors that are pivotal for the promotion of seed maturation and dormancy in angiosperms.