Saturday, April 28, 2007
My society has a long history of sponsoring undergraduate research and inviting undergraduates to present their work in a poster session at this meeting. I look forward to seeing these posters and meeting some of the undergraduates who did the work.
This is a contest. There's a prize for the best poster, I think it's several thousand dollars. Judges interview all the students who are dutifully standing by their posters. It's a lot of fun.
I took a photo of the poster session from a small balcony overlooking the giant exhibit area. This was the only session for today—all the rest start tommorrow. The reason for having the undergraduate posters first is so the prize can be awarded at a special presentation tomorrow at noon. As you can see in the photo, the poster session was well attended. By the time I got downstairs there were two or three people in front of every poster.
This was an impressive group of students. I had serious science discussions with about a dozen presenters. I don't think I could identify the winner because some of the topics were way outside my areas of knowledge but here are two posters that I liked very much.
Amit Gautam is an undergraduate at Johns Hopkins. He works with bacterial release factors. These are proteins that terminate protein synthesis and stimulate the release of the completed polypeptide chain from the translation complex (ribocsome). His particular release factor comes in two different conformations. You can see them just over his left shoulder. The compact version is what was seen when purified protein was crystallized. The elongated form was the conformation observed when the release factor was bound to the ribosome.
The extended form is almost certainly the active form since it spans the distance between the termination codon and the site where the completed polypeptide is bound to tRNA in the P site. The protein has to do this to function, that's why the compact form was a surprise when it was first discovered.
Amit reasoned that the release factor had to shift from the compact form in solution to the extended form when it attached to ribosomes. He also reasoned that if he could block that shift the release factor would not work.
Amit introduced two cysteine residues into the release factor at positions that were in close contact in the compact form but far apart in the extended form. He predicted that a disulfide bond would form when the release factor was folded into the compact form and this covalent bond would lock it into the compact form preventing, it from adopting the extended form when it bound to ribosomes. As predicted, the modified release factor formed a disulfide bridge and was unable to catalyze release.
Under reducing conditions the disulfide bridge is disrupted and the release factor regains full activity. This is a nice example of a prediction and an experiment that tests the prediction. It's a nice piece of work.
Beccy Joscwitz used the split ubiquitin yeast two hybrid system to look for proteins that interacted with a membrane protein in yeast [see Technology reveals 'lock and key' proteins behind diseases]. She's a very impressive student and seems to be right on top of the work. She knew most of the problems and she also knew when to ask questions. I think the judges were very impressed.
Beccy, like Amit, wants to be scientist. Any graduate school would be lucky to have them.