Compiled by BioPhotonics staff
CHAMPAIGN, Ill. – A new sensitive instrument that combines two molecular imaging technologies
can provide scientists with detailed insight into dynamic molecular processes.
Two physicists from the University of Illinois have combined their
expertise in single-molecule biophysics – fluorescence microscopy and optical
traps – to study the binding and unbinding of individual DNA segments to a
larger strand. Their findings appeared in Nature Methods on Feb. 20, 2011 (doi:
Physicists from the University of Illinois have developed an instrument
that uses two molecular imaging techniques to capture individual DNA segments binding
and unbinding to a larger strand.
On their own, the two techniques cannot provide the sensitivity
needed to image single DNA strands. Although fluorescence microscopy techniques
enable researchers to observe proteins as they conform and move, they lack the spatial
range to track movement over distances. Optical traps allow scientists to study
a protein’s translocation, but not its conformation, making it difficult to
know how many proteins or which types are involved.
By combining the two methods, the researchers measured both the
protein’s motion – sensitive to translocation as small as one DNA base
pair – as well as its conformational changes as it acted. Their findings revealed
details about the DNA’s mechanism that was not accessible using the two techniques
The work was supported by the National Science Foundation, National
Institutes of Health and the Howard Hughes Medical Institute.