Target DNA structure plays a critical role in Tn7 transposition.
The bacterial transposon Tn7 utilizes four Tn7-encoded proteins, TnsA, TnsB, TnsC and TnsD, to make insertions at a specific site termed attTn7. This target is selected by the binding of TnsD to attTn7 in a sequence-specific manner, followed by the binding of TnsC and activation of the transposase. We show that TnsD binding to attTn7 induces a distortion at the 5' end of the binding site and TnsC contacts the region of attTn7 distorted by TnsD. Previous work has shown that a target site containing triplex DNA, instead of TnsD-attTn7, can recruit TnsABC and effect site- specific insertion of Tn7. We propose that the DNA distortion imposed by TnsD on attTn7, like the altered DNA structure via triplex formation, serves as a signal to recruit TnsC. We also show that TnsD primarily contacts the major groove of DNA, whereas TnsC is a minor groove binding protein. The footprint of the TnsC-TnsD-attTn7 nucleoprotein complex includes and extends beyond the Tn7 insertion site, where TnsC forms a platform to receive and activate the transposase to carry out recombination.
Kuduvalli
P N
PN
Howard Hughes Medical Institute, Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, 725 N. Wolfe Street, Baltimore, MD 21205, USA.
Rao
J E
JE
Craig
N L
NL
D001426:Bacterial Proteins / Q000378:metabolism*; D001665:Binding Sites; D004247:DNA / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D004251:DNA Transposable Elements; D009690:Nucleic Acid Conformation; D013329:Structure-Activity Relationship
D001426:Bacterial Proteins; D004251:DNA Transposable Elements; D004247:DNA