buratowski steve

The Buratowski laboratory studies basic mechanisms of gene expression, more specifically the production of eukaryotic mRNA.  They use Saccharomyces cerevisiae as a model system, taking advantage of its amenability to both genetic and biochemical approaches.  The continue to characterize the initiation factors for RNA polymerase II (RNApII) and many recent projects relate to a series of phosphorylations that occur on the C-terminal domain (CTD) of the RNApII largest subunit.  The lab showed that the CTD phosphorylation pattern changes dramatically as the polymerase moves from 5' to 3' ends of a gene, essentially acting as a marker for the position of the polymerase.  These phosphorylations are used to recruit various mRNA processing and chromatin modifying complexes to specific regions of the gene as they are needed. For example, mRNA capping enzyme and the histone H3K4 methyltransferase Set1 are localized to regions near promoters, the H3K36 methyltransferase Set2 to middle regions, and polyadenylation factors to 3' ends.  The lab is exploring the function of the co-transcriptional histone methylations at H3K4 and H3K36, showing that these modifications recruit various histone deacetylases that help distinguish highly acetylated "real" promoters from cryptic promoters that occur by chance within transcribed regions.  Finally, they are working to understand the mechanisms by which RNApII transcription is terminated.  There are at least two distinct mechanisms: the classic cleavage/polyadenylation/torpedo mechanism that acts at mRNAs and a second pathway that works at short, non-polyadenylated and non-coding transcripts such as snoRNAs.