Transcriptional activation of a moderately expressed tRNA gene by a positioned nucleosome.

@article{citeulike:2109746, abstract = {All of the members of a tRNA1(Gly) multigene family from the mulberry silkworm, Bombyx mori, have identical coding regions and consequently identical internal promoter elements, but are transcribed at different levels. A moderately expressed copy, tRNA1(Gly)-4 from within this multigene family, which was transcribed to 30-50\% of the highly transcribed gene copies harboured two typical TATAA box sequences in the 5' upstream region at positions -27 nt and -154 nt with respect to the +1 nt of mature tRNA. Deletion of the distal TATAA sequence at -154 nt brought down the transcription more than 70\%, whereas mutation of the proximal element did not affect transcription. tRNA1(Gly)-4 could be readily assembled into chromatin, with a positioned nucleosome in the upstream region, and the assembled nucleosome formed stable complexes with the transcription factors TFIIIC and TFIIIB. Organization of the gene into nucleosomes also enhanced transcription significantly above that of the naked DNA, reaching transcription levels comparable with those of the highly transcribed copies. This nucleosome-mediated enhancement in transcription was absent when the distal TATAA sequences were deleted, whereas mutation of the proximal TATAA element showed no effect. In the absence of the distal TATAA sequences, assembly into the nucleosome inhibited transcription of tRNA1(Gly)-4. TFIIIB bound directly through the distal TATAA sequence at -154 nt and the positioned nucleosome facilitated its interaction with TFIIIC. The direct binding of TFIIIB to the DNA provided anchoring of the factor to the template DNA which conferred a higher stability on the TFIIIB-TFIIIC-DNA complex. We have proposed a novel mechanism for the nucleosome-mediated stimulation of pol III (RNA polymerase III) transcription of tRNA genes, a model not presented previously.}, address = {Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore-560012, India.}, author = {Parthasarthy, A. and Gopinathan, K. P. }, citeulike-article-id = {2109746}, doi = {10.1042/BJ20052029}, issn = {1470-8728}, journal = {Biochem J}, month = {June}, number = {3}, pages = {439--447}, posted-at = {2007-12-14 02:02:50}, priority = {2}, title = {Transcriptional activation of a moderately expressed tRNA gene by a positioned nucleosome.}, url = {http://dx.doi.org/10.1042/BJ20052029}, volume = {396}, year = {2006} }

TY - JOUR ID - citeulike:2109746 L3 - citeulike-article-id:2109746 TI - Transcriptional activation of a moderately expressed tRNA gene by a positioned nucleosome. JF - Biochem J VL - 396 IS - 3 SP - 439 EP - 447 AD - Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore-560012, India. SN - 1470-8728 N2 - All of the members of a tRNA1(Gly) multigene family from the mulberry silkworm, Bombyx mori, have identical coding regions and consequently identical internal promoter elements, but are transcribed at different levels. A moderately expressed copy, tRNA1(Gly)-4 from within this multigene family, which was transcribed to 30-50% of the highly transcribed gene copies harboured two typical TATAA box sequences in the 5' upstream region at positions -27 nt and -154 nt with respect to the +1 nt of mature tRNA. Deletion of the distal TATAA sequence at -154 nt brought down the transcription more than 70%, whereas mutation of the proximal element did not affect transcription. tRNA1(Gly)-4 could be readily assembled into chromatin, with a positioned nucleosome in the upstream region, and the assembled nucleosome formed stable complexes with the transcription factors TFIIIC and TFIIIB. Organization of the gene into nucleosomes also enhanced transcription significantly above that of the naked DNA, reaching transcription levels comparable with those of the highly transcribed copies. This nucleosome-mediated enhancement in transcription was absent when the distal TATAA sequences were deleted, whereas mutation of the proximal TATAA element showed no effect. In the absence of the distal TATAA sequences, assembly into the nucleosome inhibited transcription of tRNA1(Gly)-4. TFIIIB bound directly through the distal TATAA sequence at -154 nt and the positioned nucleosome facilitated its interaction with TFIIIC. The direct binding of TFIIIB to the DNA provided anchoring of the factor to the template DNA which conferred a higher stability on the TFIIIB-TFIIIC-DNA complex. We have proposed a novel mechanism for the nucleosome-mediated stimulation of pol III (RNA polymerase III) transcription of tRNA genes, a model not presented previously. AU - Parthasarthy, A AU - Gopinathan, KP PY - 2006/06/15/ UR - http://dx.doi.org/10.1042/BJ20052029 ER -