Technology Shows Protein Synthesis

Research may help explain how the same genes produce

Scientists can now observe protein production real-time inside individual cells, according to research conducted by Harvard professor X. Sunney Xie. This study, the results of which were published last week in the journals Science and Nature, represents a breakthrough in protein-imaging technology and confirms some long-held speculations about the process protein synthesis, according to the researchers.

Now, as a result of his research, “we can probe the fundamental biochemical interactions in living cells with the ultimate sensitivity, sensitivity not possible with previous technology,” said Xie, professor of chemistry and chemical biology.

Xie’s research was able to confirm speculations long-held by biologists that when protein production occurs in small numbers, it happens in fits and bursts rather than continuously, researchers said.

According to Xie, these results may ultimately help to explain how the same genes can produce different phenotypes, a problem that has baffled biologists.

Associate Professor of Chemistry and Chemical Biology and Physics Xiaowei Zhuang, who does research in the same area, said she was excited about the new possibilities opened by Xie’s research.

“Watching individual proteins being synthesized offers great opportunities for further research,” Zhuang said.

“Single molecule detection is still very new. There are a lot of fundamental types of processes that can take advantage of this type of experiment,” said Ji Yu, a research scientist that worked with Xie on the study.

The researchers were able to observe the protein production process by using fluorescent markers that will signal protein production. This enabled them to observe under a microscope a live cell expressing individual genes, and to count the protein molecules one by one inside the cell. Using this new technology, Xie created a movie of the gene expression process.

Xie’s study was funded in part by the prestigious National Institute of Science Director’s Pioneer Award, which provides half-a-million dollars per year for five years of research. Director of the National Institute of General Medical Sciences Jeremy M. Berg said of Xie’s research, “He’s a real pioneer....This is exactly the type of research we really hoped to encourage with the Director’s Pioneer award.”

The study was co-authored by graduate student Long Cai and researchers Nir Friedman and Jie Xiao.