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The ultimate mini-machine

February 16, 2011


2010 iGEM team.

2010 iGEM team members at MIT. From left: Postdoctoral adviser Swati Choudhary, Matthew Adams, Annie Kathuria, Ian Windsor, postdoctoral adviser Poonam Srivastava, and Anthony Goering. Faculty adviser Jeff Gralnick is mirrored in the 'M." 

Students win a prize for building a biological machine

By Deane Morrison

You think building a ship in a bottle is hard? Try building a factory in a bacterial cell. 

A team of five University of Minnesota undergrads did just that, and won a gold medal at a large international competition for it.

The five, all College of Biological Sciences students, took the trophy in November at the annual International Genetically Engineered Machine (iGEM) competition hosted annually by the Massachusetts Institute of Technology. It attracted 130 student teams from 25 countries, all having risen to the challenge of designing, building and testing a biological system that could operate within a cell.

"[Our] students synthesized inside bacteria a small compartment we can use to do a variety of new chemical reactions that weren't present in the cell before and that the cell would have a hard time doing on its own," says team faculty co-adviser Jeffrey Gralnick, an assistant professor in the University's Department of Microbiology and its BioTechnology Institute.

The next generation

Comments from students looking forward to being on the U's 2011 iGEM team:

• "This new area of research iGEM exploits will be extremely useful to study both how native systems work and what we can program our research model to do with these systems."—Daniele Young

• "I think iGEM is a way to better understand and experience the biology we learn in class."—Honglin Li

• "I joined the team because of the opportunity it presents to ask real questions that we can answer ourselves through research, not a book or an article."—Jessica Dent

The bacterial microcompartment, or BMC, is a factory within a bacterial cell. When confined in a BMC, chemical reactions occur efficiently, and the chamber prevents any toxic chemicals produced along the way from escaping and poisoning the cell.

BMCs hold promise for producing chemicals useful in medicine, energy, industry, agriculture, and other areas.

Cell within a cell

The project began with a harmless strain of Salmonella bacteria. These bacteria naturally construct their own BMCs out of protein molecules. The goal was to coax E. coli bacteria, which don't naturally construct BMCs, to do the same.

The U of M team isolated the Salmonella genes that direct the cell to make a BMC. They then bundled the genes into a circular strand of DNA called a plasmid. (Plasmids are the baseball cards of the microbial world, continually being picked up and exchanged, along with the genes they contain, by bacteria everywhere.) 

When the team cultured the plasmid with E. coli cells, the bacteria obligingly absorbed the plasmid and its genes; soon, they were sporting BMCs.

Next, the students had to show that the BMCs inside the E. coli cells were capable of taking up a test protein. This was crucial, because if cells can't herd selected enzymes and other needed molecules into their BMCs, the chambers are useless.

The students engineered the E. coli cells to make a protein that turns bright green when exposed to the right kind of light. Added to the protein was a small "tail" that, like a backstage pass, signals the BMC to let the protein inside.

E. coli with microcompartment.An E. coli cell containing a bacterial microcompartment (arrow)

Imagine the team's excitement when they found dense green spots inside the bacteria; these were concentrations of the green protein in BMCs.

"The project turned out to be so successful," says Claudia Schmidt-Dannert, team faculty co-adviser and professor in the University's Department of  Biochemistry, Molecular Biology and Biophysics and BioTechnology Institute. "It was nice to see how the students got more and more excited as things worked." 

2011 iGEM, here we come

The U's 2011 iGEM team is already gearing up through a class in synthetic biology, which covers the design and building of new biological structures and functions. 

Nate Davis, one of the students in the course, says synthetic biology is where biotechnology is headed.

"It's an amazingly powerful tool for solving problems … I thought it would be great to be involved in something that was really cutting edge," he remarks.

Lauren Cole, another student in the class, may sum up the general feeling: "I'm excited because we get to create our own project—it's not coming from a lab manual."

Funding for the iGEM team came from the University's BioTechnology Institute and Biocatalysis Initiative. 

Published in 2011

Tags: College of Biological Sciences

Related Links

iGEM team page

College of Biological Sciences

Jeffrey Gralnick

Claudia Schmidt-Dannert

BioTechnology Institute

Biocatalysis Initiative