BOSTON-In a region of DNA long considered a genetic wasteland, Harvard Medical School researchers have discovered a new class of gene. Most genes carry out their tasks by making a product-a protein or enzyme. This is true of those that provide the body's raw materials, the structural genes, and those that control other genes' activities, the regulatory genes. The new one, found in yeast, does not produce a protein. It performs its function, in this case to regulate a nearby gene, simply by being turned on.

Joseph Martens, Lisa Laprade, and Fred Winston found that by switching on the new gene, they could stop the neighboring structural gene from being expressed. "It is the active transcription of another gene that is regulating the process," said Martens, HMS research fellow in genetics and lead author of the June 3 Nature study .

"I cannot think of another regulatory gene such as this one," said Winston, HMS professor of genetics. The researchers have evidence that the new gene, SRG1, works by physically blocking transcription of the adjacent gene, SER3. They found that transcription of SRG1 prevents the binding of a critical piece of SER3's transcriptional machinery.

The discovery raises tantalizing questions. How does this gene-blocking occur? Do other regulatory genes work in this fashion? Does the same mechanism occur in mammals, including humans?

At the same time, SRG1 provides clues to a recent puzzle. Researchers have lately begun to suspect that the long stretches of apparently useless, or junk, DNA might possess a hidden function. In the past year, evidence has been pouring in, not just from yeast but from mammals, that these apparently silent regions produce RNAs, which are associated with transcriptional activity (see Focus, March 5, 2004 http://focus.hms.harvard.edu/2004/March5_2004/biological_chemistry.html). Yet no one has found associa
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Contact: Judith Montminy / Misia Landau
public_affairs@hms.harvard.edu
617-432-0442
Harvard Medical School
2-Jun-2004

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