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Transcription of individual $trna_{1}^{gly}$ genes from within a multigene family is regulated by transcription factor TFIIIB

Parthasarthy, Akhila and Gopinathan, Karumathil P (2005) Transcription of individual $trna_{1}^{gly}$ genes from within a multigene family is regulated by transcription factor TFIIIB. In: FEBS Journal, 272 (20). pp. 5191-5205.

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Members of a $trna_{1}^{gly}$ multigene family from the silkworm Bombyx mori have been classified based on their transcriptions in homologous nuclear extracts, into three groups of highly, moderately and poorly transcribed genes. Because all these gene copies have identical coding sequences and consequently identical promoter elements ( the A and B boxes), the flanking sequences modulate their expression levels. Here we demonstrate the interaction of transcription factor TFIIIB with these genes and its role in regulating differential transcriptions. The binding of TFIIIB to the poorly transcribed gene $trna_{1}^{gly}$-6,7 wasless stable compared with binding of TFIIIB to the highly expressedcopy, $trna_{1}^{gly}$. The presence of a 5' upstream TATA sequence closer to the coding region in $trna_{1}^{gly}$-6,7 suggested that the initial binding of TFIIIC to the A and B boxes sterically hindered anchoring of TFIIIB via direct interactions, leading to lower stability of TFIIIC-B-DNA complexes. Also, the multiple TATATAA sequences present in the flanking regions of this poorly transcribed gene successfully competed for TFIIIB reducing transcription. The transcription level could be enhanced to some extent by supplementation of TFIIIB but not by TATA box binding protein. The poor transcription of $trna_{1}^{gly}$-6,7 was thus attributed both to the formation of a less stable transcription complex and the sequestration of TFIIIB. Availability of the transcription factor TFIIIB in excess could serve as a general mechanism to initiate transcription from all the individual members of the gene family as per the developmental needs within the tissue.

Item Type: Journal Article
Publication: FEBS Journal
Publisher: Blackwell Publishing
Additional Information: Copyright for this article belongs to Blackwell Publishing.
Keywords: Bombyx mori;differential transcription;RNA pol III;transcriptional regulation;transcription factors
Department/Centre: Division of Biological Sciences > Microbiology & Cell Biology
Date Deposited: 06 Dec 2005
Last Modified: 19 Sep 2010 04:21
URI: http://eprints.iisc.ac.in/id/eprint/4309

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