Tn5 transposase with an altered specificity for transposon ends

Area of Science:

• Molecular Biology
• Genetics
• Bacterial Transposition

Background:

• Transposons are mobile genetic elements crucial for DNA rearrangement.
• Tn5 transposon movement relies on transposase (Tnp) binding to specific DNA ends.
• Methylation of the Tn5 inside end (IE) by Dam methylase inhibits Tnp binding and transposition.

Purpose of the Study:

• To isolate and characterize a hyperactive Tn5 transposase variant.
• To investigate the effect of methylation on transposase activity and end specificity.
• To develop a tool for enhanced transposition of methylated DNA elements.

Main Methods:

• Utilized DNA shuffling, a combinatorial random mutagenesis technique, to generate mutant transposase libraries.
• Screened for transposase variants exhibiting enhanced activity on methylated inside ends (IE(ME)).
• Characterized the isolated hyperactive transposase (Tnp sC7v.2.0) in vitro and in vivo.

Main Results:

• Isolated a hyperactive transposase variant, Tnp sC7v.2.0, with significantly increased activity on methylated IE sequences.
• Tnp sC7v.2.0 demonstrates wild-type levels of transposition with non-methylated outside ends (OE).
• A specific glutamate-to-valine mutation at amino acid 58 is responsible for the altered end specificity and hyperactivity.

Conclusions:

• Engineered Tn5 transposase (Tnp sC7v.2.0) overcomes methylation-mediated inhibition of transposition.
• This hyperactive transposase offers a valuable tool for genetic manipulation involving methylated DNA.
• The findings provide insights into transposase-DNA recognition mechanisms and enzyme engineering.