Biochemical genetics; studies on the molecular mechanism of transposition
is a complex genetic rearrangement process found in all organisms.
Transposition is involved in genome evolution, with the spread of
antibiotic resistance in bacteria, and with chromosome changes found in
some cancers. Transposition is biochemically very similar to the HIV-1
provirus integration reaction. In addition, transposition is likely to
offer new tools for rearranging DNA molecules in the laboratory. Thus,
this process is of considerable interest.
My laboratory is deciphering the molecular details of transposition by studying a model bacterial transposon, Tn5. Tn5
encodes a protein called a transposase that catalyzes all the steps in
transposition; transposase-transposon DNA binding, formation of a
transposon nucleoprotein complex, cleavage of the transposon DNA free
from surrounding DNA sequences, insertion of the transposon DNA into a
new genetic site. For Tn5, all of these steps occur in a simple,
defined, in vitro system. This allows us to study the detailed
biochemical effects of various transposase and DNA target site
mutations. In addition, we have, with the collaboration of Professor
Ivan Rayment's laboratory, determined the three-dimensional structure
of the transposase. This, coupled with the genetics and biochemistry,
will generate a complete structure/function picture of the transposase
and its target DNA sequences.
My laboratory is also interested in developing the Tn5 transposition system as a molecular genetic tool. Our long term goal is to develop methods that would allow in vitro combinatorial genetics to become a standard laboratory procedure.