Upstream activating sequence

About: Upstream activating sequence is a research topic. Over the lifetime, 1633 publications have been published within this topic receiving 100112 citations.

Two distinct nuclear factors bind the conserved regulatory sequences of a rabbit major histocompatibility complex class II gene.

Abstract: The constitutive coexpression of the major histocompatibility complex (MHC) class II genes in B lymphocytes requires positive, trans-acting transcriptional factors. The need for these trans-acting factors has been suggested by the reversion of the MHC class II-negative phenotype of rare B-lymphocyte mutants through somatic cell fusion with B cells or T-cell lines. The mechanism by which the trans-acting factors exert their effect on gene transcription is unknown. The possibility that two highly conserved DNA sequences, located 90 to 100 base pairs (bp) (the A sequence) and 60 to 70 bp (the B sequence) upstream of the transcription start site of the class II genes, are recognized by the trans-acting factors was investigated in this study. By using the gel electrophoresis retardation assay, a minimum of two proteins which specifically bound the conserved A or B sequence of a rabbit DP beta gene were identified in murine nuclear extracts of a B-lymphoma cell line, A20-2J. Fractionation of nuclear extract through a heparin-agarose column allowed the identification of one protein, designated NF-MHCIIB, which bound an oligonucleotide containing the B sequence and protected the entire B sequence in the DNase I protection analysis. Another protein, designated NF-MHCIIA, which bound an oligonucleotide containing the A sequence and partially protected the 3' half of this sequence, was also identified. NF-MHCIIB did not protect a CCAAT sequence located 17 bp downstream of the B sequence. The possible relationship between these DNA-binding factors and the trans-acting factors identified in the cell fusion experiments is discussed.

Coupling the GAL4 UAS system with alcR for versatile cell type‐specific chemically inducible gene expression in Arabidopsis

Abstract: The Aspergillus alc regulon encodes a transcription factor, ALCR, which regulates transcription from cognate promoters such as alcA(p). In the presence of suitable chemical inducers, ALCR activates gene expression from alcA(p). The alc regulon can be transferred to other species and can be used to control the expression of reporter, metabolic and developmental genes in response to low-level ethanol exposure. In this paper, we describe a versatile system for targeting the alc regulon to specific cell types in Arabidopsis by driving ALCR expression from the GAL4 upstream activator sequence (UAS). Large numbers of Arabidopsis lines are available in which GAL4 is expressed in a variety of spatial patterns and, in turn, drives the expression of any gene cloned downstream of the UAS. We have used a previously characterized line that directs gene expression to the endosperm to demonstrate spatially restricted ethanol-inducible gene expression. We also show that the domain of inducible gene expression can easily be altered by crossing the UAS::ALCR cassette into different driver lines. We conclude that this gene switch can be used to drive gene expression in a highly responsive, but spatially restricted, manner.

Enhanced expression of heterologous proteins by the use of a superinducible vector in budding yeast

Abstract: We report the effects of a strong overexpression of the GAL4 activator protein on the expression of UASGAL regulated genes, obtained by cloning the GAL4 gene and the GAL1-10 upstream activating sequence (UASGAL)-lacZ fusion in the same high copy number plasmid. Comparable amounts of active enzyme were obtained by host strains usually producing different levels of cloned proteins due to their different genetic background. The transformed cells constitutively produced low levels of β-galactosidase (1–2% of total proteins) both in glucose and in raffinose minimal media. Nevertheless, expression was still inducible and a tenfold induction could be rapidly obtained by the addition of 0.5% (w/v) galactose to the culture, even when glucose was still present in the medium.

Minimal enhancer elements of the leghemoglobin lba and lbc3 gene promoters from Glycine max L. have different properties.

Abstract: The characteristics of the soybean leghemoglobin lba gene promoter were analyzed and important promoter elements from the lba and lbc3 promoters were compared using transgenic Lotus corniculatus plants. A 5' deletion analysis of the lba promoter delimited two cis-acting elements controlling expression: a distal positive element (-1254, -884) required for expression and a proximal element (-285, -60) essential for full-level activity. In contrast to the corresponding region of the lbc3 promoter, the lba proximal element is unable to control expression from the heterologous CaMV 35S enhancer. The upstream positive element of the lba gene contains a position- and orientation-independent enhancer between positions (-1091, -788). The sequence of this enhancer region is conserved in the lbc3 gene upstream (-1333, -1132) of the previously assigned strong positive element (SPE; -1090, -947). The present analysis revealed some of the properties of this extended lbc3 SPE element. The extended element (-1364, -947) functions in both orientations from 5' locations whereas the SPE2 subcomponent (-1364, -1154) containing the conserved sequence is only active in the correct orientation. Removal of the SPE2 by internal deletion demonstrates that the SPE2 subcomponent is indispensable for the activity of the lbc3 upstream positive element. These results indicate that the upstream positive elements of the lba and lbc3 genes possess different properties although their conserved minimal enhancer sequence has similar function. This may reflect the differential expression of the two lb genes of Glycine max L.