Tandemly repeated hexamer sequences within the beta interferon promoter can function as an inducible regulatory element in activation by the adenovirus E1B 19-kilodalton protein.

The expression of the human beta interferon (IFN-beta) gene was activated by the adenovirus E1B-19K protein. The sequence within the IFN-beta promoter which is related to the activation was analyzed by chloramphenicol acetyltransferase (CAT) assay. The repeated hexamer units, present within the region between -109 and -65 relative to the cap site, were required for the activation of the IFN-beta gene by the E1B-19K protein. The (AAGTGA)8 region, as a typical hexamer of the consensus sequences, was tested for function in the activation by the E1B-19K protein. When the hexamer (AAGTGA)4-8 was inserted upstream of several reporter genes (such as p55cat, pdlE1A-CAT, and pE1B-CAT) which were inefficiently stimulated, the CAT activities of these fusion genes were efficiently stimulated by the E1B-19K protein. These results show that the tandemly repeated hexamer sequences within the IFN-beta promoter can function as an inducible regulatory element in the activation by the adenovirus E1B 19K protein.     

Modulation of interferon gene transcription by positive and negative cellular factors

In vivo competition experiments were designed to identify the role of trans-acting cellular factors in the virus-inducible activation of the interferon-beta promoter. Co-transfection of a constant amount of IFN-beta/CAT test gene and increasing amounts of competitive DNA containing different IFN regulatory domains into human epithelioid 293 cells identified a low abundance, positive cellular factor(s) that interacts with the IFN regulatory region. Competition of the factor decreases virus-induced and constitutive level expression of the IFN-beta promoter, and also partially inhibits expression from the SV40 promoter. Negative regulatory effects produced by factors interacting with the IFN upstream region (-135 to -202) and with the SV40 enhancer were also observed.     

Short repeated elements in the upstream regulatory region of the SUC2 gene of Saccharomyces cerevisiae.

Expression of secreted invertase from the SUC2 gene is regulated by carbon catabolite repression. Previously, an upstream regulatory region that is required for derepression of secreted invertase was identified and shown to confer glucose-repressible expression to the heterologous promoter of a LEU2-lacZ fusion. In this paper we show that tandem copies of a 32-base pair (bp) sequence from the upstream regulatory region activate expression of the same LEU2-lacZ fusion. The level of expression increased with the number of copies of the element, but was independent of their orientation; the expression from constructions containing four copies of the sequence was only twofold lower than that when the entire SUC2 upstream regulatory region was present. This activation was not significantly glucose repressible. The 32-bp sequence includes a 7-bp motif with the consensus sequence (A/C)(A/G)GAAAT that is repeated at five sites within the upstream regulatory region. Genetic evidence supporting the functional significance of this repeated motif was obtained by pseudoreversion of a SUC2 deletion mutant lacking part of the upstream region, including two copies of the 7-bp element. In three of five pseudorevertants, the mutations that restored high-level SUC2 expression altered one of the remaining copies of the 7-bp element.     

Allelic variation at the nucleotide level in Drosophila glue genes

Summary We have sequenced a 4.7 kb genomic fragment from the chromosomal region 68C of the Drosophila melanogaster wild-type strain Formosa which contains the salivary gland secretion protein genes sgs3 and sgs7. A comparison of this sequence with that from the same region of Oregon R (Garfinkel et al. 1983) shows that the major difference in this segment is a 300 bp region, corresponding to 20 of the 15 bp tandemly repeated units which compose the central coding region of sgs3 Oregon, which is absent in the Formosa strain. The order of the remaining repeated units, common to the two strains, suggests that this region is relatively stable and does not undergo frequent rearrangements or mutations. The 5 and 3 flanking sequences of the transcribed regions, which represent ca. seventy percent of our sequencing data, appear to be as strongly conserved as the transcribed sequences themselves. In the course of in vitro manipulations of the Formosa sequence, we have isolated two spontaneous deletions of repeated units in the coding region of sgs3 and discuss possible mechanisms leading to variation in sgs3 alleles.