A team of undergraduate students from the Indian Institute of Technology, Madras has picked up two top awards at the coveted annual International Genetically Engineered Machines (iGEM) competition held on November nine at the Massachusetts Institute of Technology. The team's prize-winning project involved a new method to turn on genes in bacteria using a combination of chemical inputs and heat.
Their work was judged to have made the 'best foundational advance' while also winning a special prize for the 'best engineered biological device'. A team from Slovenia was awarded the Grand Prize at iGEM, an annual winter jamboree based on the premise that undergraduates can use a set of standard biological parts to build intricate genetic machines in living cells. These 'BioBrick parts' include: genes which give cells new chemical and physical abilities; switches called 'promoters' that can be used to turn genes on and off using external signals; and 'plasmids', self-replicating DNA elements onto which genes can be assembled, then inserted into bacterial cells.
Competing among 77 teams from 22 countries the IITM project titled 'Stresskit: beating the bacterial blues' involved a new approach to turning on genes in bacteria, using a combination of chemical and physical signals. Many of the BioBrick parts in the iGEM toolkit are promoters that turn genes on in response to specific chemical signals, via sensor proteins called transcriptional regulators. In contrast, bacteria have evolved the ability to sense broad changes in their physical state, to variables such as temperature, pH, or osmotic pressure.
"The students asked in their project it would be possible to combine specific chemical control (via transcriptional regulators) and global physical sensitivity (via sigma factors) at a single promoter," says Mukund Thattai from the National centre for Biological Sciences, who advised the students on the award-winning project alongwith Guhan Jayaraman of IITM. In 2007, and NCBS team led by Thattai had won India the first iGEM prize.
Through DNA synthesis, the team generated 16 novel promoters which combined both these functions. In order to test their constructs, they used these promoters to drive the expression of Yellow Fluorescent Protein (a variant of the Nobel-prize winning Green Fluorescent Protein). Just as planned, they found that cells glowed yellow only under the correct combination of chemical and physical conditions. For example, one of the most interesting promoters (the one which won the 'Best BioBrick' award) would only cause yellow fluorescence when a chemical called IPTG was added to the growth medium, and at the same time the cells were subjected to a temperature shift.
"These promoters are a powerful addition to the bio-engineer's toolkit, since they allow genes in bacteria to be controlled in ways previously inaccessible. All these BioBrick parts have been deposited at iGEM's 'Registry of Standard Biological Parts', so that teams participating in 2010 will be able to use them in their own designs," Thattai says.
The undergraduate students in the team were Gairik Sachdeva, Hemanth Giri Rao, Nelson Vadassery, Sailaja Nori, Sayash Kumar and Sowmya Balendiran.