transposase

Introduction

Enzymes that function to cut & paste* class 2 transposons allowing mobile genetic elements to move directly from one position to another within the genome

* rather than copy & paste

Different types of transposase work in different ways. Some can bind to any part of DNA, others bind to specific sequences.

Transposase makes a staggered cut at the target site producing sticky ends, cuts out the transposon & ligates it into the target site. A DNA polymerase fills in the resulting gaps from the sticky ends & DNA ligase closes the sugar-phosphate backbone. This results in target site duplication & the insertion sites of DNA transposons may be identified by short direct repeats (a staggered cut in the target DNA filled by DNA polymerase) followed by inverted repeats (which are important for transposon excision by transposase).

Not all DNA transposons transpose through cut & paste mechanism. In some cases a replicative transposition is observed in which transposon replicates itself to a new target site.

Transposons which only move by cut & paste may duplicate if the transposition happens during S phase of the cell cycle when the 'donor' site has already been replicated, but the 'target' site has not.

More general terms

• biochemistry

Additional terms

• gene