Polypurine/polypyrimidine sequences as cis-acting transcriptional regulators

Brahmachari, Samir K and Sarkar, Partha S and Raghavan, Sowmya and Narayan, Malathy and Maiti, Amit K (1997) Polypurine/polypyrimidine sequences as cis-acting transcriptional regulators. In: Gene, 190 (1). pp. 17-26.

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Abstract

Genome sequence information has generated increasing evidence for the claim that repetitive DNA sequences present within and around genes could play a important role in the regulation of gene expression. Polypurine/polypyrimidine sequences [poly(Pu/Py)] have been observed in the vicinity of promoters and within the transcribed regions of many genes. To understand whether such sequences influence the level of gene expression, we constructed several prokaryotic and eukaryotic expression vectors incorporating poly(Pu/Py) repeats both within and upstream of a reporter gene, lacZ (encoding β-galactosidase), and studied its expression in vivo. We find that, in contrast to the situation in Escherichia coli, the presence of poly(Pu/Py) sequences within the gene does not significantly inhibit gene expression in mammalian cells. On the other hand, the presence of such sequences upstream of lacZ leads to a several-fold reduction of gene expression in mammalian cells. Similar down-regulation was observed when a structural cassette containing poly(Pu/Py) sequences upstream of lacZ was integrated into yeast chromosome V. Sequence analysis of the nine totally sequenced yeast chromosomes shows that a large number of such sequences occur upstream of ORFs. On the basis of our experimental results and DNA sequence analysis, we propose that these sequences can function as cis-acting transcriptional regulators.

Item Type:	Journal Article
Publication:	Gene
Publisher:	Elsevier Science
Additional Information:	Copyright of this article belongs to Elsevier Science.
Keywords:	Repetitive DNA;Promoter;Upstream activating sequences; Expression vectors;Down regulation;Triplex;Coding strand; Yeast genome;DNA sequence analysis.
Department/Centre:	Division of Biological Sciences > Molecular Biophysics Unit
Date Deposited:	28 Jan 2010 07:39
Last Modified:	19 Sep 2010 05:51
URI:	http://eprints.iisc.ac.in/id/eprint/24649

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