BME MS Thesis Defense - Harry Driscoll

Starts:
11:00 am on Thursday, August 22, 2013
Location:
44 Cummington Mall, Room 203
Committee:
Natalia Broude (Advisor, Chair)
Ahmad Khalil (BME)
Tom Gilmore (Biology)

“Aptamer-driven fluorescent protein complementation for detection and localization of endogenously expressed bacterial RNAs in live cells”

Abstract:
In eukaryotic cells, some mRNAs are known to localize to distinct areas of the cell where RNA is translated and the encoded protein is specifically localized. Recent studies have suggested that though prokaryotic cells lack internal compartmentalization, different RNAs are able to localize to distinct regions of the bacterial cell. Our lab is developing methods for labeling and detection of RNA with the goal of determining localization of endogenous RNAs within single cells. We currently employ an eIF4a protein-specific aptamer for RNA labeling using one of two methods. (1) Target RNA is tagged with the aptamer sequence at the 3’ end and the aptamer triggers protein complementation of two fusion proteins, each containing split EGFP and split eIF4A protein. (2) In the second method, two RNA probes, each containing a half of a split eIF4a-specific aptamer and an antisense sequence complementary to the target RNA bind the unmodified transcript through complementary interactions. This binding brings the two fragments of the split aptamer in close proximity and allows proper folding of a split aptamer. A fluorescent signal is generated by the aptamer-driven reassociation of the fusion proteins. In this work we investigate the sensitivity of the first method for detecting transcripts expressed from their natural chromosomal loci, and describe the attempts to increase the sensitivity of the method by using multiple aptamer tagging. We also present results suggesting that the second method combining protein complementation and split aptamer approach provide high sensitivity allowing detection of endogenous bacterial RNAs expressed at very low level.