אסיף מאגר המחקר החקלאי

Conserved cis-elements bind a protein complex that regulates Drosophila ras2/rop bidirectional expression

Year:

1994

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Volume :

69

Co-Authors:

Lightfoot, K., Department of Zoology, University of the Witwatersrand, Private Bag 2, Wits, 2050, South Africa
Maltby, L., Department of Zoology, University of the Witwatersrand, Private Bag 2, Wits, 2050, South Africa
Duarte, R., Department of Zoology, University of the Witwatersrand, Private Bag 2, Wits, 2050, South Africa
Veale, R., Department of Zoology, University of the Witwatersrand, Private Bag 2, Wits, 2050, South Africa
Segev, O., Department of Zoology, University of the Witwatersrand, Private Bag 2, Wits, 2050, South Africa

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Abstract:

The Drosophila ras2 promoter region exhibits bidirectional activity, as has been demonstrated for the human c-Ha-ras1 and the mouse c-Ki-ras. Here we address a unique case of ras regulation, as Drosophila ras2 provides the only example to date in which the flanking gene (rop) and its product have been isolated. A linking mechanism of control suggests a mutual interaction between the two gene products. Our studies indicate that the Drosophila ras2 promoter region shares with the human c-Ha-ras1 promoter a CACCC box and an AP-1-like sequence. A 14 bp promoter fragment which holds a CACCC element is demonstrated to interact with a specific transcription factor (factor B). This CACCC promoter element represents a stretch of imperfect palindrome. We present evidence that this factor can form a complex with another specific DNA-binding protein (factor A). The binding sites (A + B) for these protein factors are essential for 95% expression of both genes flanking the promoter (ras2 and rop). Region A consists of four overlapping consensus sequences: a TATA-like element, a DSE-like motif (the core sequence of the serum response element), a DRE octamer, which has been shown to play a role in cell proliferation, and a 5 bp direct repeat representing the GATA consensus sequence. Factor A has a very weak affinity to the full promoter region, but when complexed with factor B binding efficiency is enhanced. We also show that alterations of DNA-protein binding specificities can be achieved by supplementing the growth media with different sera. © Macmillan Press Ltd., 1994.

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