WUSTL students take silver in synthetic biology competition

Six undergraduates build a biobrick, a standard, interchangeable DNA part that can be used to make synthetic organisms

Competing against 130 teams from across the world, a team of six undergraduates from the schools of Engineering & Applied Science and Arts & Sciences at Washington University in St. Louis took silver in the foundational advance category of the International Genetically Engineered Machine (iGEM) competition this year. This is the second year WUSTL has fielded a team for the competition.

The six team members, chosen last March by the previous year’s iGEM team, are:

  • Elaine Chang,
  • Amanda Hay,
  • Zach Knudsen,
  • Brian Landry,
  • Brenden McDearmon and
  • Alice Meng.

All of the team members are juniors or seniors in biomedical engineering or biology in Arts & Sciences.

In the iGEM competition, students use standard, interchangeable biological parts called biobricks to build novel biological systems and operate them in living cells. iGEMs began with a Massachusetts Institute of Technology (MIT) short course in 2003 during which students designed blinking cells.

The next year, the course turned into a competition. Since then, teams of undergraduates have been vying against one another to design colored bacteria, buoyant bacteria and bacteria that smell like banana or wintergreen.

But it has always been bacteria. The WUSTL team, by contrast, undertook an ambitious project to add a biological system to Saccharomyces cervevisae, otherwise known as baker’s or brewer’s yeast.

One difference between bacteria and yeast is that in bacteria, proteins are encoded by a single uninterrupted DNA sequence that is copied without alteration to produce an mRNA molecule that directs the synthesis of the protein.

In yeast however, the process is much fancier. In yeast, gene coding sequences are interrupted by noncoding sequences. So when the DNA is copied into mRNA, the mRNA is then cut and pieces are spliced together to produce a shorter molecule that directs protein synthesis.

WUSTL team member Alice Meng “running a gel,” a technique for separating DNA fragments according to size.

The WUSTL plan was to build a genetic sequence that could be cut and spliced two different ways. One would make yeast that fluoresced yellow and the other would make yeast that fluoresced cyan. The color system has a switch (stolen from a fruit fly). It can be toggled on or off by galactose, a type of sugar.

So when yeast are grown with galactose, the switch is turned on, and the mRNA is spliced to make a yellow fluorescent protein. And when the yeast is grown without galactose, the switch is turned off, and the mRNA is spliced to make a cyan fluorescent protein.

The WUSTL team then designed a circular bit of DNA called a plasmid that included their genetic sequence and had “sticky” ends that would help the yeast integrate the plasmid DNA into its DNA.

The team worked on the project through the summer and into the fall.

“Since the project overlapped with classes,” Meng says, “we took a tag team approach. One person would finish part of a process and the next person who had time in their schedule would come in and do another part.

“We weren’t able to get as far as we would have liked,” Meng says. “We made all our parts but we didn’t have time to put our system into yeast and get it up and running.”

The projects were judged and prizes awarded at the iGEM 2010 Jamboree held at MIT in early November.

“Looking at all of the different projects opened my mind to all of the different things you can do with biology,” Meng says. “One team made bacteria that could detect heavy metal contaminates in drinking water and would then aggregate and precipitate out. Another took a bacteria that could break down oil and revved up that metabolic pathway.”

“I am excited to have such a dedicated group of biomedical engineering and biology undergraduate students achieve this success in genetic engineering,” says Ralph S. Quatrano, PhD, dean of the School of Engineering & Applied Science and the Spencer T. Olin Professor. “The emerging area of synthetic biology provides a tremendous opportunity for engineering students to apply their knowledge to living systems.”