|
Joseph A Martens, Lisa Laprade, Fred Winston.
Genetics, Harvard Medical School, 77 Ave Louis Pasteur, Boston, MA,
02115, USA.
Recent studies in S. cerevisiae and in humans have
demonstrated that transcription by RNA polymerase II is widespread,
including genomic regions that do not encode proteins. The roles of
such intergenic transcription are largely unknown. We have
discovered a role for one case of intergenic transcription in
studies of the S. cerevisiae SER3 gene. Our previous results
demonstrated that transcription of SER3 is tightly repressed
during growth in rich medium and that this repression requires the
Swi/Snf chromatin remodeling complex. We now show that the SER3
regulatory region is highly transcribed under repressing conditions,
producing a non-protein-coding RNA (SRG1). Expression of the
SRG1 RNA is required for repression of SER3.
Additional experiments have demonstrated that repression occurs by a
transcription interference mechanism in which SRG1
transcription across the SER3 promoter interferes with the
binding of activators. This work, then, identifies a previously
unknown class of transcriptional regulatory gene. Additional
questions currently being addressed include: 1) Is intergenic
transcription a general mechanism of repression? 2) What is the
relationship between Swi/Snf and SRG1 in repressing SER3
transcription? 3) How are these repression mechanisms overcome under
conditions that induce SER3 transcription such as amino acid
starvation? Our goal is to understand the physiological importance
of intergenic transcription as a regulator of gene expression.
Program Nr. 369C from 2004 Yeast meeting |
