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DNA binding domains in Tn3 transposase
T Maekawa1, J Amemura-Maekawa, E Ohtsubo
1Institute of Applied Microbiology, University of Tokyo, Japan.
Molecular & General Genetics : MGG
|January 1, 1993
Summary
Tn3 transposase has distinct domains for DNA binding. The N-terminal region specifically binds terminal inverted repeats, while other segments mediate non-specific DNA interactions, suggesting a multi-domain mechanism for transposition.
Area of Science:
- Molecular Biology
- Genetics
- Biochemistry
Background:
- Transposons are mobile genetic elements crucial for genome evolution.
- Tn3 transposase mediates the movement of the Tn3 element.
- Understanding transposase function requires identifying DNA-binding domains.
Purpose of the Study:
- To map the DNA-binding domains of Tn3 transposase.
- To elucidate the roles of different transposase segments in DNA recognition.
- To investigate the mechanism of specific and non-specific DNA binding.
Main Methods:
- Construction of fusion proteins between Tn3 transposase segments and beta-galactosidase.
- Nitrocellulose filter binding assays to assess DNA binding ability.
- Analysis of DNA binding specificity for terminal inverted repeat (IR) sequences.
Main Results:
- The N-terminal segment (1-242) specifically binds the 38 bp terminal inverted repeat (IR).
- The central segment (243-632) exhibits non-specific DNA binding.
- Subsegments within the N-terminal and central regions show non-specific DNA binding.
- The C-terminal segment (633-1004) lacks DNA binding ability.
Conclusions:
- Tn3 transposase possesses multiple domains, including those for non-specific DNA binding.
- Specific DNA binding arises from the combined action of two or more domains.
- The C-terminal domain likely plays a role in the catalytic activity of transposition.