Colorado State University

Our research is focused on investigating the regulation of gene expression using budding yeast, S. cerevisiae, as a model system and genetic, genomic, molecular and biochemical approaches. Our work began with studies on the basic machinery for RNA Polymerase II (RNAPII) transcription and has evolved due to a growing appreciation for the chromatin context in which our in vivo studies are performed. The long-term overall goal of our research is to understand how the transcription machinery interfaces with chromatin to regulate gene expression in living cells, and can be divided into two main areas: one stemming from our work on inactive/poised RNAPII complexes and the other on transitions in chromatin states during activation.

Inactive/poised RNAPII complexes.

The initial discovery of RNAPII bound at genes prior to their transcriptional activation occurred a quarter century ago in Drosophila. The preloading of these "poised" complexes in an inactive state is now apparent in many different organisms (yeast, flies, humans) and occurs at a diverse set of genes. We have been characterizing the poised S. cerevisiae CYC1 gene during the inactive to active transition, and find that a multitude of coactivators and chromatin remodeling complexes are essential for this transition. Intriguingly, these same factors play critical roles in pausing of RNAPII in metazoan cells, suggesting that there are universal requirements in the transition of RNAPII from a poised to an actively elongating state.

Transitions in chromatin states during activation in vivo.

RNAPII and the general transcription machinery have restricted access to genes since the eukaroytic genome is assembled and compacted into nucleosomes. The nucleosome is the basic repeating unit of chromatin and consists of 147 base pairs of DNA wrapped around an octamer of four core histones (H2A, H2B, H3 and H4). Histones and additional chromatin architectural proteins cooperate to compact chromosomal DNA 500,000-fold to fit into the cell nucleus. Therein lies the conundrum: genetic material must be organized and compacted while remaining accessible for critical biological functions, like transcription. We are characterizing a collection of cellular factors that actively participate in altering this balance to achieve the necessary outcome. These factors include histone chaperones (proteins that function to assemble and disassemble nucleosomes), and histone acetyltransferases (enzymes that modify the histones covalently).

Biochemistry is Elementary outreach program.

"The scientists are coming!"  can be heard echoing down the halls of the elementary school. As part of our work involving yeast genetics, and in collaboration with Dr. Eric Ross (BMB/CSU), we have partnered with fifth graders and their teachers in a novel outreach program. We have created and implemented a highly successful program with seven separate sessions involving hands-on activities designed to introduce genetics and biochemistry to fifth graders. Due to the inexpensive and biologically safe reagents and the detailed instructions and workbooks we have created, many scientists could offer something similar to their local community if interested in achieving broader impact.