Transposase interaction with the β sliding clamp: effects on insertion sequence proliferation and transposition rate

Area of Science:

• Microbiology
• Molecular Biology
• Genetics

Background:

• Insertion sequences (ISs) are mobile genetic elements common in prokaryotic genomes.
• IS transposases, the proteins that catalyze IS movement, often interact with the host's β sliding clamp, a DNA replication factor.
• The impact of this interaction on IS proliferation and transposition rates remains largely unknown.

Purpose of the Study:

• To investigate the proliferation of an IS1634 family member in Acidiphilium over 600 generations.
• To determine how transposase-β sliding clamp interactions influence IS mobility and chromosomal colonization.
• To assess the effect of interaction strength on transposition rates.

Main Methods:

• Purification and binding assays of IS transposases with bacterial and archaeal sliding clamps.
• In vivo transposition assays to measure the rate of IS proliferation.
• Comparative analysis of IS1634 transposase interactions across different species.

Main Results:

• The Acidiphilium IS1634 transposase binds to the β sliding clamp of Acidiphilium, Leptospirillum, and E. coli.
• Cross-species binding was observed: Acidiphilium transposase bound to archaeal PCNA, and Methanosarcina transposase bound to Acidiphilium β.
• Increased binding affinity between β and transposase correlated with higher in vivo transposition rates.

Conclusions:

• The interaction between IS transposases and host β sliding clamps is a key factor in IS proliferation and chromosomal colonization.
• The strength of this interaction can dictate the mobility and evolutionary potential of insertion sequences.
• This interaction mechanism may be conserved across diverse prokaryotic and archaeal lineages.