Study sheds light on RNA “on / off switches”

Scientists from The Scripps Research Institute have shed new light on a molecular switch that turns genes on or off in response to a cell's energy needs.

The study-published February 13, 2011 in an Advance Online Publication of the journal Nature Structural and Molecular Biology-shows these recently discovered RNA ''riboswitches'' are capable of more complex functions than originally thought. In addition, because riboswitches so far have been found primarily in bacteria, the study may have implications for designing new antibiotics against harmful bacteria.

''The study provides new insights into how a single RNA molecule can integrate both positive and negative signals from a cell,'' said senior author Martha Fedor, an associate professor and member of the Skaggs Institute for Chemical Biology at Scripps Research. ''It extends the known capabilities of riboswitches.''

Riboswitches respond to the concentrations of molecules produced by a cell's metabolism-the process of creating or using energy-to regulate genes' activities. The new study shows that a particular riboswitch does not respond to just a single metabolite, as had been assumed, but rather to many such compounds.

Switching genes on and off

Each gene serves as a recipe for building a protein molecule. When a particular protein is needed by the cell, the corresponding gene, made of DNA, is turned ''on,'' or transcribed into a messenger RNA, which then carries the ''protein recipe'' to the protein-making machinery of the cell.