SEPTEMBER 20 - Dr. Vikki Weake

Announcements

National FFA Convention- Thursday, October 25 - There are 4 time slots that are 50 minutes long (10am-3:50pm).  Email Gabe if you are interested in helping out at grangel@purude.edu.

Celebrate Science Indiana (CSI)- Saturday, October 6 - At the Indianapolis Fairgrounds, at 8:30am-4pm.  There are rides available to the fairgrounds from campus, but you can also meet us there if you live nearby.  Email Gabe if you are interested or have questions at grangel@purude.edu.

 

Old Business

The week of September 10-15, Biochemistry Club Outreach went to Cumberland Elementary School, and had a great time.

The week of September 10-15, the grant for the Biochemistry Club Outreach was turned in.  We will find out soon whether our grant was accepted. 

New Business

T-shirt design has been made.  The shirts this year will have the saying “I         BCHM”, but the heart is a flask instead.  The shirts will cost around $8.  We will have more information next meeting. 

Speaker- Dr. Vikki Weake

Novel Functions of Metazoan SAGA

Eukaryotic DNA is compacted into chromatin, which makes chromosomes.  Histones, which are found on chromatins, are subjected to post-translation modification.  These modifications include acetylation, methylation, phosphorylation, and ubiquitination (addition of small protein).  The modifications tell the cell what type of nucleosome it has.  Nucleosomes can be moved or displaced by chromatin remodelers.  Mutations of chromatin remodeling genes are found in cancer patients, so correct chromatin remodeling is critically to human health. 

Transcription factors, or activators, bind to specific DNA sequences.  They recruit co-activators, or mediators, which in turn recruits the transcription machinery, bringing in RNA polymerase I.  SAGA is a transcription co-activator, which is essential for viability in metazoans.  This means it plays critical roles in multicellular development.  SAGA is mis-regulated in cancer and neurodengative disease.  There are two histone modifications SAGA is involved in: acetylation stimulates chromatin remolding, and ubiquition removal. 

SAGA in fly vs. SAGA in yeast- To compare the SAGA, epitope-tagged SAGA subunits were purified from cell cultures.  In yeast a subset of TAF proteins were found.  In Drosophila the SAGA contains other novel proteins, mainly 2 splicing proteins. 

SAGA in Neuron Cells vs. SAGA in Muscle Cells- There is tissue specific expression of epitope-tagged SAGA.  The SAGA subunits all were present in the muscle and neuron cells.  SAGA binds to distinct genes in embryonic muscle and neuron (binds to different genes).  There is more transcription factors present in SAGA from the muscle relative to neurons.

Glial cells are found in the brain, and are very important in development.  In SAGA mutations, glial cells stop in the wrong place, and can cause vision defects.  This means that SAGA is associated with tissue-specific defects.

 

Purdue University | Purdue Biochemistry