In a cell, DNA contained in genes directs the synthesis of specific proteins that determine the function of that cell. These functions have to be turned on and off in a precise manner for the cell to operate normally. Carlos Bustamante, Ph.D. , a National Science Foundation-supported researcher at the Institute of Molecular Biology at the University of Oregon, has reported in the journal Science recently the results of studies that reveal how this happens.
Proteins bind to specific regions of DNA to inhibit expression of one or more genes.
To do this, they must have an efficient mechanism for recognition, and must discriminate between non-specific and specific sites by binding more tightly to the latter. SFM can reveal the extent of DNA bending induced by protein binding to non-specific and specific sites. SFM works like a phonograph, scanning a surface underneath a tip and sensing the deflections of the tip. These deflections can be amplified and recorded to provide a topographic map of the surface. Bustamante has studied the binding of Cro, a protein that regulates genes in bacterial viruses, to DNA containing non-specific and specific binding sites.