Factors determining frequency of plasmid cointegration mediated by insertion sequence IS1

Area of Science:

• Molecular Biology
• Genetics
• Microbiology

Background:

• Insertion sequences (IS) are mobile genetic elements.
• IS1 is a well-studied IS element involved in various genetic rearrangements.

Purpose of the Study:

• To elucidate the functional domains and genes of IS1 essential for cointegration.
• To investigate the mechanism of IS1-mediated cointegration and transposon formation.

Main Methods:

• Site-directed mutagenesis of IS1 to create deletion and insertion mutants.
• Plasmid-based assays to measure cointegration frequencies.
• Nucleotide sequence analysis of IS1 mutants.

Main Results:

• Deletions at IS1 ends abolish cointegration; internal mutations reduce it.
• Both IS1 ends (insL, insR) and genes (insA, insB) are crucial for cointegration.
• IS1-encoded proteins can function in trans, with location affecting efficiency.

Conclusions:

• IS1 cointegration requires specific terminal sequences and internal genes.
• IS1-encoded proteins exhibit trans-complementation, with preferential action on their source sequence.
• Plasmid location influences IS1 protein production and cointegration frequency.