Guanosine triphosphate acts as a cofactor to promote assembly of initial P-element transposase–DNA synaptic complexes

TLDR: Atomic force microscopy is used to visualize protein-DNA complexes formed during the initial stages of P-element transposition and reveals that GTP acts to promote assembly of the first detectable noncovalent precleavage synaptic complex.

Abstract: P transposable elements in Drosophila are members of a larger class of mobile elements that move using a cutand-paste mechanism. P-element transposase uses guanosine triphosphate (GTP) as a cofactor for transposition. Here, we use atomic force microscopy (AFM) to visualize protein–DNA complexes formed during the initial stages of P-element transposition. These studies reveal that GTP acts to promote assembly of the first detectable noncovalent precleavage synaptic complex. This initial complex then randomly and independently cleaves each P-element end. These data show that GTP acts to promote protein–DNA assembly, and may explain why Pelement excision often leads to unidirectional deletions.