The completion of the human genome may have answered some of medical researches fundamental questions, however, the discovery has led to more complex questions for scientists. One in particular has left researchers studying gene control perplexed, "How is it that humans, being far more complex than the lowly yeast, do not proportionally contain in our genome significantly more gene-control proteins?"
A collaboration among scientists at the Johns Hopkins School of Medicine that examined protein-DNA interactions across the whole genome may have an answer. Researchers have uncovered more than 300 proteins that appear to control genes, a heretofore undiscovered function for these proteins that were previously known to play other roles in cells. The results, which appear in the Oct. 30 issue of Cell, provide a partial explanation for human complexity over yeast but also throw a curve ball in what we previously understood about protein functions.
"Everyone knows that transcription factors bind to DNA and everyone knows that they bind in a sequence-specific manner," says Heng Zhu, Ph.D., an assistant professor in pharmacology and molecular sciences and a member of the High Throughput Biology Center. "But you only find what you look for, so we looked beyond and discovered proteins that essentially moonlight as transcription factors."
The team suspects that many more proteins encoded by the human genome might also be moonlighting to control genes, which brings researchers to the paradox that less complex organisms, such as plants, appear to have more transcription factors than humans. "Maybe most of our genes are doing double, triple or quadruple the work," says Zhu. "This may be a widespread phenomenon in humans and the key to how we can be so complex without significantly more genes than organisms like plants."
Source: Heng Zhu, Ph.D., Johns Hopkins
Writer: Walaika Haskins