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Intrinsic bends and integration host factor binding at F plasmid oriT
M M Tsai1, Y H Fu, R C Deonier
1Department of Biological Sciences, University of Southern California, Los Angeles 90089-1340.
Journal of Bacteriology
|August 1, 1990
Summary
This study analyzed the F plasmid oriT DNA for DNA bending and integration host factor (IHF) binding. Results show intrinsic DNA curvature and specific IHF binding sites, suggesting a structural role in oriT function.
Area of Science:
- Molecular Biology
- Genetics
- Biochemistry
Background:
- The F plasmid's origin of transfer (oriT) is crucial for bacterial conjugation.
- Understanding oriT DNA structure and protein interactions is key to deciphering DNA transfer mechanisms.
Purpose of the Study:
- To investigate the intrinsic DNA bending within the F plasmid oriT region.
- To identify and characterize the binding sites of integration host factor (IHF) on oriT DNA.
Main Methods:
- Permutation assays were used to detect intrinsic DNA bends.
- Gel retardation and DNase footprinting assays were employed to study IHF binding.
Main Results:
- A 527-bp fragment of F plasmid oriT exhibited intrinsic bending, with curvature centered around base pair 240.
- Two primary bending components were localized near base pairs 170 and 260.
- Integration host factor (IHF) bound to a major site (bp 165-195) and a minor site (bp 287-319) within the oriT sequence.
Conclusions:
- The intrinsic curvature of oriT DNA and IHF binding sites likely contribute to the structural organization and function of the origin of transfer.
- These structural features may play a significant role in regulating plasmid conjugation initiation.