Three distinct regulatory elements comprise the upstream promoter region of the nopaline synthase gene

Summary Fine deletion mutants were generated in the upstream control region of the nopaline synthase (nos) promoter to define the position and role of upstream regulatory elements. The results indicated that the 8 bp sequence (CAGAAACC) at -106/-113 and its inverted repeat (GGTTTCTG) at -140/-147 are important for promoter function. The downstream element appears more important than the upstream element since deletion of the former reduced promoter activity more significantly than deletion of the latter. Deletion of the element alone, however, did not abolish promoter function, whereas, deletion of the 10 bp potential Z-DNA-forming (Z) element located between the repeat elements nullified promoter activity. Therefore, it appears that the Z element is an essential upstream regulator and the repeated elements are upstream modulators of the nos promoter. These elements are functionally distinct since alteration of stereospecificity or insertion of short oligonucleotides between the elements did not significantly influence promoter activity. These regulatory elements were unable to function from 200 bp upstream of the CCAAT-TATA box region.     

Functional analyses of the maize CKS2 gene promoter in response to abiotic stresses and hormones

In our previous research, we showed that the cyclin-dependent kinase regulatory subunit (CKS2) in maize (Zea mays L.) was induced by water deficit and cold stress. To elucidate its expression patterns under adversity, we isolated and characterized its promoter (PZmCKS2). A series of PZmCKS2-deletion derivatives, P0–P3, from the translation start code (?1,455, ?999, ?367, and ?3 bp) was fused to the β-glucuronidase (GUS) reporter gene, and each deletion construct was analyzed by Agrobacterium-mediated steady transformation into Arabidopsis. Leaves were then subjected to dehydration, cold, abscisic acid (ABA), salicylic acid (SA), and methyl jasmonic acid (MeJA). Sequence analysis showed that several stress-related cis-acting elements (MBS, CE3, TGA element, and ABRE) were located within the promoter. Deletion analysis of the promoter, PZmCKS2, suggested that the ?999 bp promoter region was required for the highest basal expression of GUS, and the ?367 bp sequence was the minimal promoter for ZmCKS2 activation by low temperature, ABA, and MeJA. The cis-acting element ABRE was necessary for promoter activation by exogenous ABA.     

Functional dissection of a napin gene promoter: identification of promoter elements required for embryo and endosperm-specific transcription

The promoter region (?309 to +44) of the Brassica napus storage protein gene napA was studied in transgenic tobacco by successive 5′ as well as internal deletions fused to the reporter gene GUS (β-glucuronidase). The expression in the two main tissues of the seed, the endosperm and the embryo, was shown to be differentially regulated. This tissue-specific regulation within the seed was found to affect the developmental expression during seed development. The region between ?309 to ?152, which has a large effect on quantitative expression, was shown to harbour four elements regulating embryo and one regulating endosperm expression. This region also displayed enhancer activity. Deletion of eight bp from position ?152 to position ?144 totally abolished the activity of the napA promoter. This deletion disrupted a cis element with similarity to an ABA-responsive element (ABRE) overlapping with an E-box, demonstrating its crucial importance for quantitative expression. An internal deletion of the region ?133 to ?120, resulted in increased activity in both leaves and endosperm and a decreased activity in the embryo. Within this region, a cis element similar to the (CA)_n element, found in other storage protein promoters, was identified. This suggest that the (CA)_n element is important for conferring seed specificity by serving both as an activator and a repressor element.     

Two distinct P element subfamilies in the genome of Drosophila bifasciata

The genome of Drosophila bifasciata harbours two distinct subfamilies of P-homologous sequences, designated M-type and O-type elements based on similarities to P element sequences from other species. Both subfamilies have some general features in common: they are of similar length (M-type: 2935 bp, O-type: 2986 bp), are flanked by direct repeats of 8 by (the presumptive target sequence), contain terminal inverted repeats, and have a coding region consisting of four exons. The splice sites are at homologous positions and the exons have the coding capacity for proteins of 753 amino acids (M-type) and 757 amino acids (O-type). It seems likely that both types of element represent functional transposons. The nucleotide divergence of the two P element subfamilies is high (31%). The main structural difference is observed in the terminal inverted repeats. Whereas the termini of M-type elements consist of 31 by inverted repeats, the inverted repeats of the O-type elements are interrupted by non-complementary stretches of DNA, 12 by at the 5′ end and 14 by at the 3′ end. This peculiarity is shared by all members of the O-type subfamily. Comparison with other P element sequences indicates incongruities between the phylogenies of the species and the P transposons. M-type and O-type elements apparently have no common origin in the D. bifasciata lineage. The M-type sequence seems to be most closely related to the P element from Scaptomyza pallida and thus could be considered as a more recent invader of the D. bifasciata gene pool. The origin of the O-type elements cannot be unequivocally deduced from the present data. The sequence comparison also provides new insights into conserved domains with possible implications for the function of P transposons.