Mariner Mos1 transposase dimerizes prior to ITR binding

Area of Science:

• Molecular Biology
• Genetics
• Biochemistry

Background:

• The mariner Mos1 synaptic complex assembles transposase tetramers to facilitate DNA end joining.
• Protein-protein interactions, specifically cis- and trans-dimerization, are essential for this assembly.
• Understanding these interfaces is key to elucidating the transposase mechanism.

Purpose of the Study:

• To precisely define the protein regions responsible for cis- and trans-dimerization in the mariner Mos1 transposase.
• To investigate the role of these interfaces in the formation and function of the synaptic complex.
• To identify the active species involved in DNA binding.

Main Methods:

• Biochemical assays were employed to analyze protein-protein interactions.
• Genetic methods were utilized to probe the function of specific amino acid residues and regions.
• Analysis focused on the N-terminal region of the Mos1 transposase.

Main Results:

• Both cis- and trans-dimerization interfaces are located within the first 143 amino acid residues.
• Amino acids 1-20 are primarily involved in cis-dimerization.
• Residues 116-143, including the WVPHEL motif, mediate the cis- to trans-dimerization shift and stabilize trans-dimerization.
• The transposase cis-dimer, not the monomer, is the active species for inverted terminal repeat (ITR) binding.
• The catalytic domain influences transposase interactions even without DNA.

Conclusions:

• The N-terminal region of Mos1 transposase contains critical interfaces for dimerization and synaptic complex formation.
• The cis-dimer is the functional unit for initial DNA binding, transitioning to trans-dimerization for catalysis.
• These findings provide a detailed molecular understanding of mariner transposase function.