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Solution structure of the Tn3 resolvase-crossover site synaptic complex.
Marcelo Nöllmann1, Jiuya He, Olwyn Byron
1Division of Molecular Genetics, Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow G11 6NU, Scotland, United Kingdom.
Molecular Cell
|October 8, 2004
Summary
Tn3 resolvase mutants form a simpler X synapse. Structural analysis reveals DNA segments are outside the tetramer core, offering insights into DNA recombination mechanisms.
Area of Science:
- Molecular Biology
- Structural Biology
- Biochemistry
Background:
- Tn3 resolvase is a site-specific DNA recombinase crucial for DNA exchange.
- Natural synaptic complexes involve twelve resolvase subunits and two res sites.
- Hyperactive mutants form simpler X synapses with a tetramer and shorter DNA segments.
Purpose of the Study:
- To determine the low-resolution solution structure of the catalytically competent X synapse.
- To elucidate the quaternary structure of the resolvase tetramer in the X synapse.
- To understand the arrangement of DNA segments within the X synapse.
Main Methods:
- Small-angle neutron and X-ray scattering (SANS/SAXS) were employed.
- Data were fitted using models based on rigid body transformations.
- A published crystallographic structure of a resolvase dimer bound to site I was utilized.
Main Results:
- The X synapse structure was solved at low resolution.
- Two site I DNA fragments were located on the exterior of the resolvase tetramer core.
- Information regarding the quaternary structure of the tetramer was obtained.
Conclusions:
- The structure provides insights into the architecture of the natural synaptic complex.
- The findings contribute to understanding the mechanism of DNA strand exchange.
- The arrangement of DNA and protein components in the X synapse was clarified.