 |
T7
DNA Polymerase Structure
 |
Electron
micrograph of the
bacteriophage T7. |
A virus is usually viewed as a problem,
but T7 turned out to be useful, even
valuable. In 1982, Brookhaven National
Laboratory scientists, led by biologist
William Studier, finished determining
the DNA sequence of T7, a bacteriophage
(bacteria-eating virus) that had the
longest DNA sequence then known. When
T7 invades a host cell, it makes proteins
that turn off the host genes and turn
on T7 genes. Researchers correlated
the genetic map with T7's protein
production, thereby acquiring a detailed
understanding of how such viruses
control their own replication. Studier
and colleagues used this knowledge
to develop a series of T7-based protein
expression systems in which the gene
of interest is silent until its expression
is induced by a simple chemical trigger
added to the culture. The protein
products then are produced in abundance,
even if the host cells eventually
fail. In addition, the target genes
can be engineered so that the proteins
produced carry "affinity tags" enabling
their rapid purification.
Scientific Impact:
Widely used in molecular genetics
and biotechnology, T7 protein expressions
systems are noted for their reliability
and adaptability. Even gene products
that are difficult to express (e.g.,
toxic products) can be successfully
produced using these systems.
Social Impact: The
T7 system has become one of the most
commercially successful, biologically
based systems for producing large
quantities of specific proteins. Even
basic research using these systems
sometimes has a practical impact,
as in the case of recent work on a
protein associated with Lyme disease
that led to the development of improved
vaccines.
Reference: Studier,
F.W. and B.A. Moffatt, "Use of bacteriophage
T7 RNA polymerase to direct selective
high-level expression of cloned genes,"
J. Mol. Biol. 189: 113-130
(1986).
Studier, F.W., A.H. Rosenberg, J.J.
Dunn and J.W. Dubendorff, "Use of
T7 RNA polymerase to direct expression
of cloned genes," Methods in Enzymology
185:60-89 (1990).
URL:
http://bnlstb.bio.bnl.gov/biodocs/cellbio/Studier.htmlx
Technical Contact:
Dr. Marvin Stodolsky, Life Sciences
Division, Office of Biological and
Environmental Research, 301-903-4742
Press Contact: Jeff
Sherwood, DOE Office of Public Affairs,
202-586-5806
SC-Funding Office:
Office of Biological and Environmental
Research |
